0001514416-21-000167 | 10-Q | XBRL Viewer

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Cover - shares	3 Months Ended
Cover - shares	Mar. 31, 2021	Apr. 30, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-38285
Entity Registrant Name	BANDWIDTH INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	56-2242657
Entity Address, Address Line One	900 Main Campus Drive
Entity Address, City or Town	Raleigh
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27606
City Area Code	(800)
Local Phone Number	808-5150
Title of 12(b) Security	Class A Common Stock, par value $0.001 per share
Trading Symbol	BAND
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001514416
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Class A voting common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		22,879,349
Class B voting common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		2,215,170

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 319,731	$ 72,163
Restricted cash	9,527	9,274
Other investments	10,000	40,000
Accounts receivable, net of allowance for doubtful accounts	51,458	55,243
Prepaid expenses and other current assets	13,386	14,508
Deferred costs	2,572	2,411
Total current assets	406,674	193,599
Property and equipment, net	50,660	51,645
Operating right-of-use asset, net	18,008	19,491
Intangible assets, net	232,804	248,055
Deferred costs, non-current	3,795	3,604
Other long-term assets	2,029	1,975
Goodwill	356,379	372,239
Total assets	1,070,349	890,608
Current liabilities:
Accounts payable	9,360	11,665
Accrued expenses and other current liabilities	55,884	63,065
Current portion of deferred revenue	6,519	6,515
Advanced billings	4,242	5,429
Operating lease liability, current	5,594	5,515
Total current liabilities	81,599	92,189
Other liabilities	1,635	1,707
Operating lease liability, net of current portion	15,609	17,202
Deferred revenue, net of current portion	6,592	6,386
Deferred tax liability	57,328	61,005
Convertible senior notes	464,848	282,196
Total liabilities	627,611	460,685
Stockholders’ equity:
Class A and Class B common stock	25	24
Additional paid-in capital	492,778	451,463
Accumulated deficit	(54,821)	(49,505)
Accumulated other comprehensive income	4,756	27,941
Total stockholders’ equity	442,738	429,923
Total liabilities and stockholders’ equity	$ 1,070,349	$ 890,608

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 113,479	$ 68,518
Cost of revenue	61,328	36,359
Gross profit	52,151	32,159
Operating expenses:
Research and development	13,333	9,530
Sales and marketing	11,992	9,417
General and administrative	26,863	16,096
Total operating expenses	52,188	35,043
Operating loss	(37)	(2,884)
Other expense, net	(5,611)	(906)
Loss before income taxes	(5,648)	(3,790)
Income tax benefit	332	2,732
Net loss	$ (5,316)	$ (1,058)
Net loss per share, basic and diluted (in usd per share)	$ (0.21)	$ (0.04)
Weighted average number of common shares outstanding, basic and diluted (in shares)	25,015,948	23,563,569

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (5,316)	$ (1,058)
Other comprehensive loss
Foreign currency translation, net of income taxes	(23,185)	(96)
Other comprehensive loss	(23,185)	(96)
Total comprehensive loss	$ (28,501)	$ (1,154)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Condensed Consolidated Statements of Changes in Stockholders’ Equity - USD ($) $ in Thousands	Total	Conversion of Class B voting common stock to Class A voting common stock	Class A voting common stock	Class B voting common stock	Common stock Class A voting common stock	Common stock Class A voting common stock Conversion of Class B voting common stock to Class A voting common stock	Common stock Class B voting common stock	Common stock Class B voting common stock Conversion of Class B voting common stock to Class A voting common stock	Additional paid-in capital	Accumulated other comprehensive (loss) income	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2019					18,584,478		4,927,401
Beginning balance at Dec. 31, 2019	$ 270,090				$ 19		$ 5		$ 275,553	$ 41	$ (5,528)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of debt conversion option	104,553								104,553
Debt conversion option issuance costs, net of tax	(3,731)								(3,731)
Capped call option purchase price	(43,320)								(43,320)
Exercises of vested stock options (in shares)					32,059
Exercises of vested stock options	244								244
Vesting of restricted stock units (in shares)					103,824
Equity awards withheld for tax liability (in shares)					(14,411)
Equity awards withheld for tax liability	(1,021)								(1,021)
Conversion of Class B voting common stock to Class A voting common stock (in shares)						500,250		(500,250)
Conversion of Class B voting common stock to Class A voting common stock		$ (1)						$ (1)
Foreign currency translation	(96)									(96)
Stock based compensation	2,499								2,499
Net loss	(1,058)										(1,058)
Ending balance (in shares) at Mar. 31, 2020					19,206,200		4,427,151
Ending balance at Mar. 31, 2020	328,159				$ 19		$ 4		334,777	(55)	(6,586)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Debt conversion option issuance costs, net of tax	(11)								(11)
Exercises of vested stock options (in shares)					502,182
Exercises of vested stock options	3,297				$ 1				3,296
Vesting of restricted stock units (in shares)					21,871
Equity awards withheld for tax liability (in shares)					(2,133)
Equity awards withheld for tax liability	(272)								(272)
Conversion of Class B voting common stock to Class A voting common stock (in shares)						827,597		(827,597)
Foreign currency translation	(23)									(23)
Stock based compensation	2,425								2,425
Net loss	(20,641)										(20,641)
Ending balance (in shares) at Jun. 30, 2020					20,555,717		3,599,554
Ending balance at Jun. 30, 2020	312,934				$ 20		$ 4		340,215	(78)	(27,227)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercises of vested stock options (in shares)					44,848
Exercises of vested stock options	386								386
Vesting of restricted stock units (in shares)					17,948
Equity awards withheld for tax liability (in shares)					(2,002)
Equity awards withheld for tax liability	(350)								(350)
Conversion of Class B voting common stock to Class A voting common stock (in shares)						606,418		(606,418)
Conversion of Class B voting common stock to Class A voting common stock		0				$ 1		$ (1)
Foreign currency translation	139									139
Stock based compensation	2,382								2,382
Net loss	(2,352)										(2,352)
Ending balance (in shares) at Sep. 30, 2020					21,222,929		2,993,136
Ending balance at Sep. 30, 2020	313,139				$ 21		$ 3		342,633	61	(29,579)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercises of vested stock options (in shares)					13,995
Exercises of vested stock options	149								149
Vesting of restricted stock units (in shares)					17,424
Equity awards withheld for tax liability (in shares)					(1,749)
Equity awards withheld for tax liability	(273)								(273)
Conversion of Class B voting common stock to Class A voting common stock (in shares)						497,011		(497,011)
Conversion of Class B voting common stock to Class A voting common stock		(1)						$ (1)
Equity consideration for Voxbone acquisition (in shares)					663,394
Equity consideration for Voxbone acquisition	106,380				$ 1				106,379
Foreign currency translation	27,880									27,880
Stock based compensation	2,575								2,575
Net loss	(19,926)										(19,926)
Ending balance (in shares) at Dec. 31, 2020			22,413,004	2,496,125	22,413,004		2,496,125
Ending balance at Dec. 31, 2020	429,923				$ 22		$ 2		451,463	27,941	(49,505)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of debt conversion option	66,908								66,908
Debt conversion option issuance costs, net of tax	(2,049)								(2,049)
Capped call option purchase price	(25,500)								(25,500)
Exercises of vested stock options (in shares)					57,817
Exercises of vested stock options	753								753
Vesting of restricted stock units (in shares)					141,707
Equity awards withheld for tax liability (in shares)					(19,879)
Equity awards withheld for tax liability	(3,187)								(3,187)
Conversion of Class B voting common stock to Class A voting common stock (in shares)						280,955		(280,955)
Conversion of Class B voting common stock to Class A voting common stock		$ 1				$ 1
Foreign currency translation	(23,185)									(23,185)
Stock based compensation	4,390								4,390
Net loss	(5,316)										(5,316)
Ending balance (in shares) at Mar. 31, 2021			22,873,604	2,215,170	22,873,604		2,215,170
Ending balance at Mar. 31, 2021	$ 442,738				$ 23		$ 2		$ 492,778	$ 4,756	$ (54,821)

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020
Cash flows from operating activities
Net loss	$ (5,316)	$ (19,926)	$ (20,641)	$ (1,058)
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities
Depreciation and amortization	9,043			3,298
Right-of-use asset amortization	1,347			1,158
Amortization of debt discount and issuance costs	5,186			1,753
Stock-based compensation	4,390			2,499
Deferred taxes	(1,095)			(2,337)
Loss on disposal of property and equipment	201			233
Changes in operating assets and liabilities:
Accounts receivable, net of allowances	3,530			(6,899)
Prepaid expenses and other assets	925			(991)
Deferred costs	(352)			(396)
Accounts payable	1,387			304
Accrued expenses and other liabilities	(6,913)			(4,991)
Deferred revenue and advanced billings	(953)			1,105
Operating right-of-use liability	(1,371)			(1,285)
Net cash (used in) provided by operating activities	10,009			(7,607)
Cash flows from investing activities
Purchase of property and equipment	(6,781)			(3,638)
Capitalized software development costs	(1,103)			(790)
Proceeds from sales and maturities of other investments	30,000			0
Net cash (used in) provided by investing activities	22,116			(4,428)
Cash flows from financing activities
Payments on finance leases	(44)			0
Proceeds from issuance of convertible senior notes	250,000			400,000
Payment of debt issuance costs	(7,000)			(11,048)
Purchase of capped call	(25,500)			(43,320)
Proceeds from exercises of stock options	738			244
Value of equity awards withheld for tax liabilities	(2,900)			(960)
Net cash provided by financing activities	215,294			344,916
Effect of exchange rate changes on cash, cash equivalents and restricted cash	402			(25)
Net increase in cash, cash equivalents, and restricted cash	247,821			332,856
Cash, cash equivalents, and restricted cash, beginning of period	81,437		$ 517,860	185,004
Cash, cash equivalents, and restricted cash, end of period	329,258	$ 81,437		517,860
Supplemental disclosure of cash flow information
Cash paid for interest	525			0
Cash refunded for taxes	(394)			(229)
Supplemental disclosure of noncash investing and financing activities
Purchase of property and equipment, accrued but not paid	1,780			2,595
Equity awards withheld for tax liabilities, accrued but not paid	531			238
Payment of debt issuance costs, accrued but unpaid	$ 659			$ 875

Organization and Description of Business	3 Months Ended
Organization and Description of Business	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	1. Organization and Description of Business Bandwidth Inc. (together with its subsidiaries, “Bandwidth” or the “Company”) was founded in July 2000 and incorporated in Delaware on March 29, 2001. The Company’s headquarters are located in Raleigh, North Carolina. The Company is an international cloud-based, software-powered communications platform-as-a-service (“CPaaS”) provider that enables enterprises to create, scale and operate voice or messaging communications services across any mobile application or connected device. The Company has two operating and reportable segments, CPaaS and Other. CPaaS revenue is derived from usage and monthly services fees charged for usage of Voice, Messaging, 911 and Phone Numbers solutions through the Company’s proprietary CPaaS software application programming interfaces. Other revenue consists of fees charged for services provided such as: SIP trunking, data resale, and a hosted Voice-over Internet Protocol (“VoIP”). The Other segment also includes revenue from traffic generated by other carriers, SMS registration fees and other miscellaneous product lines. On November 2, 2020, the Company acquired all of the A Ordinary Shares, B Ordinary Shares and C Ordinary Shares of Voice Topco through a Share Purchase Agreement. Voice Topco directly or indirectly held all of the issued and outstanding shares of Voxbone S.A., which (with its subsidiaries) was the operating subsidiary of Voice Topco (“Voxbone)”. The transaction was valued at €446 million. As consideration for the Share Purchase, the Company (i) paid the selling stockholders approximately $400 million (or approximately €338 million based on prevailing exchange rates at the close of business on October 9, 2020) at the Closing and (ii) issued to the selling stockholders at the Closing shares of the Company’s Class A common stock, with an aggregate value of approximately €108 million (or approximately $128 million based on prevailing exchange rates at the close of business on October 9, 2020). Due to the timing and magnitude of the transaction and multi-jurisdictional nature of the net assets acquired, initial accounting for the acquisition is not complete, and further measurement adjustments may occur in fiscal year 2021. The Company will reflect measurement period adjustments in the period in which the adjustments are determined.

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Certain information and disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K filed with the SEC on March 1, 2021. The condensed consolidated balance sheet as of December 31, 2020, included herein, was derived from the audited financial statements as of that date, but does not include all disclosures, including certain notes required by GAAP on an annual reporting basis. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full year 2021 or any future period. Principles of Consolidation The condensed consolidated financial statements include the accounts of Bandwidth Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires the Company to make estimates and judgments that affect the amounts reported in these financial statements and accompanying notes. These estimates in the condensed consolidated financial statements include, but are not limited to, allowance for doubtful accounts, reserve for expected credit losses, reserve for sales credits, recoverability of long lived and intangible assets, fair value of acquired intangible assets and goodwill, discount rates used in the valuation of right-of-use assets and lease liabilities, the fair value of the liability and equity components of the Company’s Convertible Notes (as defined herein), estimated period of benefit, valuation allowances on deferred tax assets, certain accrued expenses and contingencies, economic and demographic actuarial assumptions related to pension and other postretirement benefit costs and liabilities, estimated cash flows on asset retirement obligation. Although the Company believes that the estimates it uses are reasonable, due to the inherent uncertainty involved in making these estimates, actual results reported in future periods could differ from those estimates. Cash and Cash Equivalents The Company classifies all highly liquid investments with original stated maturities of three months or less from the date of purchase as cash equivalents and all highly liquid investments with original stated maturities of greater than three months from the date of purchase as current marketable securities, with the exception of time deposits which are classified as other investments. Cash deposits are primarily in financial institutions in the United States. However, cash for monthly operating costs of international operations are deposited in banks outside the United States. The Company has a policy of making investments only with commercial institutions that have at least an investment grade credit rating. The Company utilizes money market funds as an investment option and only invests in AAA rated funds. Restricted Cash Restricted cash consists primarily of the holdback amount remaining to be paid to the selling stockholders of Voxbone, employee withholding tax liability and employee benefits contributions not yet remitted. The Company has classified this asset as a short-term asset in order to match the expected period of restriction. Accounts Receivable and Current Expected Credit Losses Accounts receivable are stated at realizable value, net of allowances, which includes an allowance for doubtful accounts and a reserve for expected credit losses. The allowance for doubtful accounts is based on management’s assessment of the collectability of its customer accounts. The Company regularly reviews the composition of the accounts receivable aging, historical bad debts, changes in payment patterns, customer creditworthiness, current economic trends, and reasonable and supportable forecasts about the future. Relevant risk characteristics include customer size and historical loss patterns. Management has evaluated the expected credit losses related to trade accounts receivable and determined that allowances of approximately $1,203 and $1,218 for uncollectible accounts and customer balances that are disputed were required as of December 31, 2020 and March 31, 2021, respectively. Refer to Note 4, “Financial Statement Components” to these condensed consolidated financial statements, for a rollforward of the components of the allowances as of December 31, 2020 and March 31, 2021. The Company includes unbilled receivables in its accounts receivable balance. Generally, these receivables represent services provided to customers, which will be billed in the next billing cycle. All amounts are considered collectible and billable. As of December 31, 2020 and March 31, 2021, unbilled receivables were $27,692 and $28,490, respectively. Concentration of Credit Risk Financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents, other investments and trade accounts receivable. Cash deposits may be in excess of insured limits. The Company believes that the financial institutions that hold its cash deposits are financially sound and, accordingly, minimal credit risk exists with respect to these balances. With regard to customers, credit evaluation and account monitoring procedures are used to minimize the risk of loss. The Company believes that no additional credit risk beyond amounts provided for by the allowance for doubtful accounts are inherent in accounts receivable. As of December 31, 2020, one individual customer represented approximately 11% of the Company’s accounts receivable, net of allowance for doubtful accounts. As of March 31, 2021, one individual customer represented approximately 12% of the Company’s accounts receivable, net of allowance for doubtful accounts. For the three months ended March 31, 2020 and 2021, no individual customer represented more than 10% of the Company’s total revenue. Debt Issuance Costs The Company incurs debt issuance costs associated with obtaining and entering into credit agreements, including the issuances of convertible notes. These costs customarily include non-refundable structuring fees, commitment fees, up-front fees and syndication expenses. The Company has a policy of deferring and amortizing these costs based on the effective interest method over the term of the credit agreements. Recently Adopted Accounting Standards In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted, including adoption in an interim period. The Company adopted this standard on a prospective basis, which did not have a material impact on the Company’s financial statements. Recent Accounting Pronouncements Not Yet Adopted In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40), which is intended to address issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. For convertible instruments, ASU 2020-06 reduces the number of accounting models for convertible debt instruments and convertible preferred stock, and enhances information transparency by making targeted improvements to the disclosures for convertible instruments and earnings-per-share (EPS) guidance on the basis of feedback from financial statement users. ASU 2020-06 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2021. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company is evaluating the effect of adopting this new accounting guidance on its financial statements and earnings per share calculations, but does not intend to early adopt.

Fair Value Measurements

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

The carrying amounts of cash and cash equivalents, other investments, accounts receivable, accounts payable and accrued expenses approximate fair value as of December 31, 2020 and March 31, 2021 because of the relatively short duration of these instruments.

The Company evaluated its financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level in which to classify them for each reporting period.

The following table summarizes the assets measured at fair value as of December 31, 2020 and March 31, 2021:


				Fair value measurements on a recurring basis December 31, 2020
	Level 1	Level 2	Level 3	Total
Financial assets:
Cash and cash equivalents:
Money market account				$	57,517	$	—	$	—	$	57,517








Other investments:
Time deposits				40,000		—		—		40,000

Total financial assets				$	97,517	$	—	$	—	$	97,517


				Fair value measurements on a recurring basis March 31, 2021
	Level 1	Level 2	Level 3			Total
Financial assets:
Cash and cash equivalents:
Money market account				$	283,504		$	—	$	—	$	283,504
Time deposits				15,000			—		—		15,000



Total included in cash and cash equivalents				298,504			—		—		298,504




Other investments:
Time deposits				10,000			—		—		10,000

Total financial assets				$	308,504		$	—	$	—	$	308,504

As of March 31, 2021, the fair value of the 2026 and 2028 Convertible Notes, as further described in Note 8, “Debt”, was approximately $609,698 and $245,206, respectively. The fair value was determined based on the closing price for the Convertible Notes on the last trading day of the reporting period and is considered as Level 2 in the fair value hierarchy.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Financial Statement Components

3 Months Ended

Mar. 31, 2021

Financial Statement Components [Abstract]

Financial Statement Components

4. Financial Statement Components

Accounts receivable, net of allowances consist of the following:


	As of December 31,		As of March 31,
	2020		2021
Trade accounts receivable	$	26,504	$	22,591
Unbilled accounts receivable	27,692		28,490
Allowance for doubtful accounts and reserve for expected credit losses	(1,203)		(1,218)
Other accounts receivable	2,250		1,595
Total accounts receivable, net	$	55,243	$	51,458

Components of allowance for doubtful accounts and reserve for expected credit losses are as follows:


	Three months ended March 31,
		2020		2021
Allowance for doubtful accounts:
Balance, beginning of period		$	(769)	$	(1,203)
Charged to bad debt expense		(189)		(48)
Deductions (1)		75		10
Impact of foreign currency translation		—		23



Balance, end of period		$	(883)	$	(1,218)

________________________

(1) Write off of uncollectible accounts after all collection efforts have been exhausted.

Accrued expenses and other current liabilities consisted of the following:


	As of December 31,		As of March 31,
	2020		2021
Accrued expense	$	31,549	$	32,476
Accrued compensation and benefits	19,534		11,531
Accrued sales, use, VAT and telecommunications related taxes	9,142		9,114

Other accrued expenses	2,657		2,588
Current portion of finance lease	183		175
Total accrued expenses and other current liabilities	$	63,065	$	55,884

Right-of-Use Asset and Lease Liabilities

3 Months Ended

Mar. 31, 2021

Leases [Abstract]

Right-of-Use Asset and Lease Liabilities

5. Right-of-Use Asset and Lease Liabilities

Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The Company determines if an arrangement is a lease at inception. ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Operating lease expense attributable to lease payments is recognized on a straight-line basis over the lease term and is included in cost of sales and selling, general, and administrative expense on the Company’s condensed consolidated statements of operations. Finance leases result in the recognition of depreciation expense, which is recognized on a straight-line basis over the expected life of the leased asset, and interest expense, which is recognized following an effective interest rate method. Depreciation expense attributable to finance leases is included in cost of sales on the Company’s condensed consolidated statements of operations. The Company presents the operating leases in long-

term assets and current and long-term liabilities in the accompanying condensed consolidated balance sheets. Finance leases are reported in property and equipment, net, accrued expenses and other current liabilities, and other liabilities on the Company’s condensed consolidated balance sheets.

The Company sub-leases approximately 17,073 square feet of office space to a related party, Republic Wireless, Inc. (“Republic”). Future minimum sub-lease receipts required under the non-cancellable lease are as follows:


	As of March 31,
	2021
2021 (remaining)	$	345
2022	249



	$	594

As of March 31, 2021, the Company had various leased properties in the United States and internationally, with remaining lease terms of eight months to 5.75 years, some of which include options to extend the leases for up to 5 years. None of the options to extend the leases are recognized in operating lease ROU assets or lease liabilities. The Company has one lease with an early-termination option, which it does not expect to exercise.

The components of lease expense recorded in the condensed consolidated statement of operations were as follows:


	Three months ended March 31,
		2020		2021
Operating lease cost		$	1,461	$	1,614
Finance lease cost:
Depreciation of assets		—		47



Sublease income (1)		(96)		(96)
Total net lease cost		$	1,365	$	1,565

________________________

(1) See Note 15, “Related Parties” to these condensed consolidated financial statements, for additional details on sublease income.

During the three months ended March 31, 2020 and 2021, short-term operating lease expense were $0 and $345, respectively.

Supplemental balance sheet information related to leases was as follows:


		As of December 31,		As of March 31,
Leases	Classification	2020		2021
Assets:
Operating lease assets	Operating right-of-use asset, net (1)	$	19,491	$	18,008
Finance lease assets	Property and equipment, net (2)	464		428
Total leased assets		$	19,955	$	18,436

Liabilities:
Current
Operating	Operating lease liability, current	$	5,515	$	5,594
Finance	Accrued expenses and other current liabilities	183		175
Non-current
Operating	Operating lease liability, net of current portion	17,202		15,609
Finance	Other liabilities	282		258
Total lease liabilities		$	23,182	$	21,636

________________________

(1) Operating lease assets are recorded net of accumulated amortization of $9,083 and $10,435 as of December 31, 2020 and March 31, 2021, respectively.

(2) Finance lease assets are recorded net of accumulated depreciation of $28 and $74 as of December 31, 2020 and March 31, 2021, respectively.

Supplemental cash flow and other information related to leases was as follows:


	Three months ended March 31,
		2020			2021
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases		$	1,285		$	1,371

Financing cash flows from finance leases		—			44
		$	1,285		$	1,415

Weighted average remaining lease term (in years)
Operating leases		4.11			3.53
Finance leases		—			2.86

Weighted average discount rate
Operating leases		4.99		%	4.81		%
Finance leases		—		%	4.00		%

Maturities of operating lease liabilities were as follows:


	As of March 31,
	2021
2021 (remaining)	$	4,756
2022	6,736
2023	6,593
2024	2,670
2025	1,648

Thereafter	718
Total lease payments	23,121
Less: imputed interest	(1,918)

Total lease obligations	21,203
Less: current obligations	(5,594)
Long-term lease obligations	$	15,609

Maturities of financing lease liabilities were as follows:


	As of March 31,
	2021
2021 (remaining)	$	147
2022	148
2023	97
2024	61
2025	4


Total lease payments	457
Less: imputed interest	(24)

Total lease obligations	433
Less: current obligations	(175)
Long-term lease obligations	$	258

Property and Equipment

3 Months Ended

Mar. 31, 2021

Property, Plant and Equipment [Abstract]

Property and Equipment

6. Property and Equipment

Property and equipment, net consisted of the following:


	As of December 31,		As of March 31,
	2020		2021
Furniture and fixtures	$	2,341	$	2,348
Computer and office equipment	4,077		4,190
Telecommunications equipment	60,651		61,753
Leasehold improvements	6,285		6,280
Software	3,901		4,877
Internal-use software development	19,968		20,884
Automobile	502		512
Total cost	97,725		100,844
Less—accumulated depreciation	(46,080)		(50,184)
Total property and equipment, net	$	51,645	$	50,660

The Company capitalized $790 and $1,103 of software development costs for the three months ended March 31, 2020 and 2021, respectively.

Amortization expense related to capitalized software development costs were $582 and $420 for the three months ended March 31, 2020 and 2021, respectively. As of March 31, 2021, unamortized implementation costs related to cloud computing arrangements are $533, of which $140 are included in prepaid expenses and other current assets and $393 are included in other long-term assets.

The Company leases automobiles under leases accounted for as finance leases with expiration dates ranging from December 31, 2021 to April 30, 2025. As of March 31, 2021, cost and accumulated depreciation of the assets under finance leases recorded by the Company were $502 and $74, respectively.

The Company recognized depreciation expense, which includes amortization of capitalized software development costs, as follows:


	Three months ended March 31,
		2020		2021
Cost of revenue		$	2,334	$	3,033
Research and development		115		240
Sales and marketing		29		29
General and administrative		690		874
Total depreciation expense		$	3,168	$	4,176

Intangible Assets

3 Months Ended

Mar. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

7. Intangible Assets

Intangible assets, net consisted of the following as of December 31, 2020:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,111)	$	5,285	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquistion and other intangible assets	15,093		(9,044)		6,049

Voxbone acquistion:
Customer relationships	156,559		(1,739)		154,820		15
Developed technology	88,664		(1,478)		87,186		10
Total Voxbone acquisition	245,223		(3,217)		242,006

Total intangible assets, net	$	260,316	$	(12,261)	$	248,055

Intangible assets, net consisted of the following as of March 31, 2021:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,241)	$	5,155	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquisition and other intangible assets	15,093		(9,174)		5,919

Voxbone acquisition:
Customer relationships	149,764		(4,161)		145,603		15
Developed technology	84,816		(3,534)		81,282		10
Total Voxbone acquisition	234,580		(7,695)		226,885

Total intangibles, net	$	249,673	$	(16,869)	$	232,804

Amortization expense for definite lived intangible assets was $130 and $4,867 for the three months ended March 31, 2020 and 2021, respectively. The remaining weighted average amortization period for definite lived intangible assets is 13 years.

Future estimated amortization expense for definite lived intangible assets is as follows:


	As of March 31,
	2021
2021 (remaining)	$	14,239
2022	18,986
2023	18,986
2024	18,986
2025	18,986


Thereafter	141,857
	$	232,040

Debt

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Debt

8. Debt

Revolving Loan

On March 10, 2021, the Company entered into a waiver agreement with respect to its revolving loan (the “Credit Facility”) with KeyBank National Association and Pacific Western Bank (the “Lenders”), which provides for consent to accommodate the issuance of the 2028 Convertible Notes and entry into the 2028 Capped Calls (as defined below).

As of December 31, 2020, unamortized debt issuance costs were $83, of which $74 were in included in prepaid expenses and other current assets and $9 were included in other long-term assets. As of March 31, 2021, the outstanding debt issuance costs are $64, which are included in prepaid expenses and other current assets.

As of December 31, 2020 and March 31, 2021, the Company had $0 outstanding on the Credit Facility and was in compliance with all financial and non-financial covenants for all periods presented. The available borrowing capacity under the Credit Facility was $25,000 as of March 31, 2021.

The Convertible Notes, described below, are effectively subordinate to the Company’s existing and future senior secured indebtedness including the Company’s $25,000 Credit Facility, to the extent of the value of the collateral securing that indebtedness. The Convertible notes are the senior, unsecured obligations of the Company and are equal in right of payment with the Company’s existing and future senior unsecured indebtedness, senior in right of payment to the Company’s existing and future indebtedness that is expressly subordinated to the Convertible Notes and the Convertible Notes will be structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables, and preferred equity, if any, of the Company’s subsidiaries.

Convertible Senior Notes and Capped Call Transactions

2026 Convertible Notes

On February 28, 2020, the Company issued $400,000 aggregate principal amount of 0.25% Convertible Notes due March 1, 2026 in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act (the “2026 Convertible Notes,” and together with the 2028 Convertible Notes, the “Convertible

Notes”). The interest on the 2026 Convertible Notes is payable semi-annually in arrears on March 1 and September 1 of each year, beginning on September 1, 2020.

The 2026 Convertible Notes may bear special interest under specified circumstances relating to the Company's failure to comply with its reporting obligations under the indenture governing the 2026 Convertible Notes (the “2026 Indenture”) or if the 2026 Convertible Notes are not freely tradeable as required by the 2026 Indenture. The 2026 Convertible Notes will mature on March 1, 2026, unless earlier repurchased, redeemed by the Company, or converted pursuant to their terms. The total net proceeds from the 2026 Convertible Notes, after deducting initial purchaser discounts, costs related to the 2026 Capped Calls, and debt issuance costs, paid by the Company, were approximately $344,722.

Each $1 principal amount of the 2026 Convertible Notes is initially convertible into 10.9857 shares of the Company's Class A common stock, par value $0.001 per share, which is equivalent to an initial conversion price of approximately $91.03 per share. The conversion rate is subject to adjustment upon the occurrence of certain specified events but will not be adjusted for any accrued and unpaid special interest. In addition, upon the occurrence of a make-whole fundamental change, as defined in the 2026 Indenture, the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its 2026 Convertible Notes in connection with such make-whole fundamental change or during the relevant redemption period.

The 2026 Convertible Notes will be redeemable in whole or in part at the Company's option on or after March 6, 2023, but before the 40th scheduled trading day before the maturity date, at a cash redemption price equal to 100% of the principal amount of the 2026 Convertible Notes to be redeemed, plus accrued and unpaid interest, if any, if the last reported sale price of the Class A common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading days ending on, and including, the trading day immediately before the date the redemption notices were sent; and the trading day immediately before such notices were sent.

Prior to the close of business on the business day immediately preceding September 1, 2025, the 2026 Convertible Notes may be convertible at the option of the holders only under the following circumstances:

(1)during any calendar quarter commencing after the calendar quarter ending on June 30, 2020 (and only during such calendar quarter), if the last reported sale price per share of the Company's Class A common stock exceeds 130% of the conversion price for each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter;

(2)during the five consecutive business days immediately after any 10 consecutive trading day period (such 10 consecutive trading day period, the “measurement period”) in which the trading price per $1 principal amount of 2026 Convertible Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company's Class A common stock on such trading day and the conversion rate on such trading day;

(3)upon the occurrence of certain corporate events or distributions on its Class A common stock; and

(4)if the Company calls such 2026 Convertible Notes for redemption.

On or after September 1, 2025, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders of the 2026 Convertible Notes may, at their option, convert all or a portion of their 2026 Convertible Notes regardless of the foregoing conditions.

During the three months ended March 31, 2021, the conditional conversion feature of the 2026 Convertible Notes was triggered as the last reported sale price of the Company's Class A common stock was more than or equal

to 130% of the conversion price for at least 20 trading days (whether or not consecutive) in the period of 30 consecutive trading days ending on or after June 30, 2020 (the last trading day of the calendar quarter), and therefore the 2026 Convertible Notes were convertible, in whole or in part, at the option of the holders between July 1, 2020 through March 31, 2021. Whether the 2026 Convertible Notes will be convertible following such period will depend on the continued satisfaction of this condition or another conversion condition in the future. The Company continues to classify the 2026 Convertible Notes as a long-term liability in its condensed consolidated balance sheet as of March 31, 2021, based on contractual settlement provisions.

Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of Class A common stock, or a combination of cash and shares of Class A common stock, at the Company's election. It is the Company's current intent to settle the principal amount of the 2026 Convertible Notes with cash.

No sinking fund is provided for the 2026 Convertible Notes. Upon the occurrence of a fundamental change (as defined in the 2026 Indenture) prior to the maturity date, holders may require the Company to repurchase all or a portion of the 2026 Convertible Notes for cash at a price equal to the principal amount of the 2026 Convertible Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

In accounting for the issuance of the 2026 Convertible Notes, the Company separated the 2026 Convertible Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was $125,160 and was determined by deducting the fair value of the liability component from the par value of the 2026 Convertible Notes. The difference represents the debt discount that is amortized to interest expense at an effective interest rate of 6.763% over the term of the 2026 Convertible Notes. The carrying amount of the equity component was $57,491 and is recorded in additional paid-in-capital. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount, or the debt discount, is amortized to interest expense at an annual effective interest rate of 6.807% over the contractual terms of the 2026 Convertible Notes.

In accounting for the transaction costs related to the 2026 Convertible Notes, the Company allocated the total amount incurred to the liability and equity components of the 2026 Convertible Notes based on the proportion of the proceeds allocated to the debt and equity components. Issuance costs attributable to the liability component were approximately $8,217, were recorded as an additional debt discount and are amortized to interest expense using the effective interest method over the contractual terms of the 2026 Convertible Notes. Issuance costs attributable to the equity component of $3,742 were netted with the equity component in stockholders’ equity.

2028 Convertible Notes

On March 16, 2021, the Company issued $250,000 aggregate principal amount of 0.50% Convertible Notes due April 1, 2028 in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act (the “2028 Convertible Notes”). The interest on the 2028 Convertible Notes is payable semi-annually in arrears on April 1 and October 1 of each year, beginning on October 1, 2021.

The 2028 Convertible Notes may bear special interest under specified circumstances relating to the Company's failure to comply with its reporting obligations under the indenture governing the 2028 Convertible Notes (the “2028 Indenture”) or if the 2028 Convertible Notes are not freely tradeable as required by the 2028 Indenture. The 2028 Convertible Notes will mature on April 1, 2028, unless earlier repurchased, redeemed by the Company, or converted pursuant to their terms. The total net proceeds from the 2028 Convertible Notes, after deducting initial purchaser discounts, costs related to the 2028 Capped Calls, and debt issuance costs, paid by the Company, were approximately $216,845.

Each $1 principal amount of the 2028 Convertible Notes is initially convertible into 5.5781 shares of the Company's Class A common stock, par value $0.001 per share, which is equivalent to an initial conversion price of

approximately $179.27 per share. The conversion rate is subject to adjustment upon the occurrence of certain specified events but will not be adjusted for any accrued and unpaid special interest. In addition, upon the occurrence of a make-whole fundamental change, as defined in the 2028 Indenture, the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its 2028 Convertible Notes in connection with such make-whole fundamental change or during the relevant redemption period.

The 2028 Convertible Notes will be redeemable in whole or in part at the Company's option on or after April 6, 2025, but before the 40th scheduled trading day before the maturity date, at a cash redemption price equal to 100% of the principal amount of the 2028 Convertible Notes to be redeemed, plus accrued and unpaid interest, if any, if the last reported sale price of the Class A common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading days ending on, and including, the trading day immediately before the date the redemption notices were sent; and the trading day immediately before such notices were sent.

On or after April 6, 2025 until the close of business on the scheduled trading day immediately preceding the maturity date, the 2028 Convertible Notes may be convertible at the option of the holders only under the following circumstances:

(1)during any calendar quarter commencing after the calendar quarter ending on June 30, 2021 (and only during such calendar quarter), if the last reported sale price per share of the Company's Class A common stock exceeds 130% of the conversion price for each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter;

(2)during the five consecutive business days immediately after any 10 consecutive trading day period (such 10 consecutive trading day period, the “measurement period”) in which the trading price per $1 principal amount of 2028 Convertible Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company's Class A common stock on such trading day and the conversion rate on such trading day;

(3)upon the occurrence of certain corporate events or distributions on its Class A common stock; and

(4)if the Company calls such 2028 Convertible Notes for redemption.

On or after October 1, 2027, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders of the 2028 Convertible Notes may, at their option, convert all or a portion of their Convertible Notes regardless of the foregoing conditions.

No sinking fund is provided for the 2028 Convertible Notes. Upon the occurrence of a fundamental change (as defined in the 2028 Indenture) prior to the maturity date, holders may require the Company to repurchase all or a portion of the 2028 Convertible Notes for cash at a price equal to the principal amount of the 2028 Convertible Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

In accounting for the issuance of the 2028 Convertible Notes, the Company separated the 2028 Convertible Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was $66,908 and was determined by

deducting the fair value of the liability component from the par value of the 2028 Convertible Notes. The difference represents the debt discount that is amortized to interest expense at an effective interest rate of 5.125% over the term of the 2028 Convertible Notes. The carrying amount of the equity component was $39,359 and is recorded in additional paid-in-capital. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount, or the debt discount, is amortized to interest expense at an annual effective interest rate of 4.966% over the contractual terms of the 2028 Convertible Notes.

In accounting for the transaction costs related to the 2028 Convertible Notes, the Company allocated the total amount incurred to the liability and equity components of the 2028 Convertible Notes based on the proportion of the proceeds allocated to the debt and equity components. Issuance costs attributable to the liability component were approximately $5,607, were recorded as an additional debt discount and are amortized to interest expense using the effective interest method over the contractual terms of the 2028 Convertible Notes. Issuance costs attributable to the equity component of $2,049 were netted with the equity component in stockholders’ equity.

The net carrying amount of the liability components of the 2026 and 2028 Convertible Notes were as follows:


	As of December 31,		As of March 31,
	2020		2021
2026 Convertible Notes:
Principal	$	400,000	$	400,000
Unamortized discount	(110,546)		(106,036)
Unamortized debt issuance costs	(7,258)		(6,962)
2026 Convertible Notes net carrying amount	282,196		287,002

2028 Convertible Notes:
Principal	—		250,000
Unamortized discount	—		(66,575)
Unamortized debt issuance costs	—		(5,579)
2028 Convertible Notes net carrying amount	—		177,846
Total net carrying amount	$	282,196	$	464,848

The net carrying amount of the equity components of the 2026 and 2028 Convertible Notes were as follows:


	As of December 31,		As of March 31,
	2020		2021
2026 Convertible Notes:
Proceeds allocated to the conversion options (debt discount)	$	125,152	$	125,152
Issuance costs	(3,742)		(3,742)
2026 Convertible Notes net carrying amount	121,410		121,410

2028 Convertible Notes:
Proceeds allocated to the conversion options (debt discount)	—		66,908
Issuance costs	—		(2,049)
2028 Convertible Notes net carrying amount	—		64,859
Total net carrying amount	$	121,410	$	186,269

The following table sets forth the interest expense recognized related to the 2026 and 2028 Convertible Notes:


	Three months ended March 31,
		2020		2021
2026 Convertible Notes:
Contractual interest expense		$	96	$	250
Amortization of debt discount		1,629		4,510
Amortization of debt issuance costs		106		296
Total interest expense related to the 2026 Convertible Notes		1,831		5,056

2028 Convertible Notes:
Contractual interest expense		—		52
Amortization of debt discount		—		333
Amortization of debt issuance costs		—		28
Total interest expense related to the 2028 Convertible Notes		—		413
Total interest expense		$	1,831	$	5,469

In connection with the offering of the 2026 and the 2028 Convertible Notes, the Company entered into privately negotiated capped call transactions with certain counterparties (the “2026 Capped Calls” and the “2028 Capped Calls,” respectively, and collectively, the “Capped Calls”). The 2026 Capped Calls and the 2028 Capped Calls each have an initial strike price of approximately $91.03 and $179.27 per share, respectively, subject to certain adjustments, which corresponds to the initial conversion price of the 2026 and the 2028 Convertible Notes. The 2026 Capped Calls and the 2028 Capped Calls have initial cap prices of $137.40 and $260.76 per share subject to certain adjustments, respectively. The 2026 Capped Calls and the 2028 Capped Calls cover, subject to anti-dilution adjustments, approximately 4,394,276 and 1,917,472 shares of Class A common stock for the 2026 Convertible Notes and 2028 Convertible Notes, respectively. The Capped Calls are generally intended to reduce or offset the potential dilution to the Class A common stock upon any conversion of the 2026 Convertible Notes and 2028 Convertible Notes with such reduction or offset, as the case may be, subject to a cap based on the cap price. The Capped Calls expire on the earlier of (i) the last day on which any convertible securities remain outstanding and (ii) March 1, 2026 for the 2026 Capped Calls and April 1, 2028 for the 2028 Capped Calls, subject to earlier exercise. The Capped Calls are subject to either adjustment or termination upon the occurrence of specified extraordinary events affecting the Company, including a merger event, a tender offer, and a nationalization, insolvency or delisting involving the Company. In addition, the Capped Calls are subject to certain specified additional disruption events that may give rise to a termination of the Capped Calls, including changes in law, insolvency filings, and hedging disruptions. The Capped Call transactions are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost of $43,320 and $25,500 incurred to purchase the 2026 Capped Calls and the 2028 Capped Calls, respectively, was recorded as a reduction to additional paid-in capital in the accompanying condensed consolidated balance sheets.

Segment and Geographic Information

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Segment and Geographic Information

9. Segment and Geographic Information

The Company has two reportable segments, CPaaS and Other. Segments are primarily evaluated based on revenue and gross profit. The Company does not allocate operating expenses, interest expense or income tax expense to its segments. Accordingly, the Company does not report such information. Additionally, the Chief Operating Decision Maker does not evaluate the Company’s operating segments using discrete asset information. The segments share the majority of the Company’s assets. Therefore, no segment asset information is reported.


	Three months ended March 31,
		2020		2021
CPaaS
Revenue		$	59,121	$	100,146
Cost of revenue		31,892		53,681
Gross profit		$	27,229	$	46,465
Other
Revenue		$	9,397	$	13,333
Cost of revenue		4,467		7,647
Gross profit		$	4,930	$	5,686
Consolidated
Revenue		$	68,518	$	113,479
Cost of revenue		36,359		61,328
Gross profit		$	32,159	$	52,151

The Company’s long-lived assets were primarily held in the United States as of December 31, 2020 and March 31, 2021. As of December 31, 2020 and March 31, 2021, long-lived assets held outside of the United States were $11,249 and $10,537, respectively.

The Company generates its revenue primarily in the United States. Revenue by geographic area is detailed in the table below (which is determined based on the customer billing address):


	Three months ended March 31,
		2020		2021
CPaaS
United States		$	57,398	$	88,862
International		1,723		11,284
Total		$	59,121	$	100,146

Other
United States		$	9,125	$	11,936
International		272		1,397
Total		$	9,397	$	13,333

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Stockholders' Equity

3 Months Ended

Mar. 31, 2021

Equity [Abstract]

Stockholders' Equity

10. Stockholders’ Equity

Preferred Stock

As of December 31, 2020 and March 31, 2021, the Company had authorized 10,000,000 shares of undesignated preferred stock, par value $0.001, of which no shares were issued and outstanding.

Common Stock

As of December 31, 2020 and March 31, 2021, the Company had authorized 100,000,000 shares of Class A common stock, par value $0.001 per share, with one vote per share and 20,000,000 shares of Class B common stock, par value $0.001 per share, with ten votes per share. As of December 31, 2020, 22,413,004 and 2,496,125 shares of Class A common stock and Class B common stock, respectively, were issued and outstanding. As of

March 31, 2021, 22,873,604 and 2,215,170 shares of Class A common stock and Class B common stock, respectively, were issued and outstanding.

Shares of Class B common stock are convertible into shares of Class A common stock upon the stockholder’s voluntary written notice to the Company’s transfer agent or a transfer by the stockholder, subject to limited exceptions for transfers for estate planning purposes.

Reserved Shares

The Company had reserved shares of Class A common stock for issuance under stock-based award agreements as follows:


	As of December 31,	As of March 31,
	2020	2021
Stock options issued and outstanding	255,000	196,433
Nonvested restricted stock units issued and outstanding	450,614	405,875
Stock-based awards available for grant under the 2017 Plan	2,020,342	3,044,024
	2,725,956	3,646,332

Stock Based Compensation

3 Months Ended

Mar. 31, 2021

Share-based Payment Arrangement [Abstract]

Stock Based Compensation

11. Stock Based Compensation

2010 Stock Option Plan

As of July 26, 2010, the Company adopted the 2010 Equity Compensation Plan (the “2010 Plan”). On November 9, 2017, the 2010 Plan was terminated in connection with the Company’s initial public offering. Accordingly, no shares are available for future issuance under the 2010 Plan. However, the 2010 Plan continues to govern the terms and conditions of the outstanding awards granted thereunder.

2017 Incentive Award Plan

The Company’s 2017 Incentive Award Plan (the “2017 Plan”) became effective on November 9, 2017. The 2017 Plan provides for the grant of stock options, including incentive stock options and non-qualified stock options, stock appreciation rights, restricted stock, dividend equivalents, restricted stock units, and other stock or cash based awards to employees, consultants and directors of the Company. A total of 1,050,000 shares of the Company’s Class A common stock were originally reserved for issuance under the 2017 Plan. These available shares automatically increase each January 1, beginning on January 1, 2018, by 5% of the number of shares of the Company’s Class A common stock outstanding on the final day of the immediately preceding calendar year. On January 1, 2021, the shares available for grant under the 2017 Plan were automatically increased by 1,120,650 shares.

The terms of the stock option grants are determined by the Company’s Board of Directors. The Company’s stock options vest based on terms of the stock option agreements, which is generally over four years. The stock options have a contractual life of ten years.

Restricted stock units (“RSUs”) granted under the 2017 Plan are generally subject to a time-based vesting condition. The compensation expense related to these awards is based on the grant date fair value of the RSUs and is recognized on a ratable basis over the applicable service period. The Company granted RSUs to its non-employee members of the Board of Directors, some of which vested immediately while others vest 25% as of each calendar quarter immediately following the grant date. Certain RSUs awarded to executives vest over four years with 50% vesting in the first year in 12.5% increments on each calendar quarter immediately following the grant date and the remaining 50% earned over years two, three and four. Other RSUs awarded to executives and employees generally are earned over a service period of four years.

Stock Options

The following summarizes the stock option activity for the periods presented:


	Number of options outstanding	Weighted- average exercise price (per share)		Weighted- average remaining contract life (in years)	Aggregate intrinsic value (in thousands)
Outstanding as of December 31, 2020	255,000	$	10.82	4.42	$	36,426
Granted	—	—
Exercised	(57,817)	13.02			7,697
Forfeited or cancelled	(750)	9.57
Outstanding as of March 31, 2021	196,433	$	10.18	4.18	$	22,897

Options vested and exercisable at March 31, 2021	170,100	$	8.95	3.83	$	20,035
Options vested and expected to vest as of March 31, 2021	195,810	$	10.16	4.18	$	22,828

Aggregate intrinsic value is computed based on the difference between the option exercise price and the fair value of the Company’s common stock as of March 31, 2021, based on the Company’s Class A common stock price as reported on the NASDAQ Global Select Market.

No options were granted for the three months ended March 31, 2020 and 2021.

The total estimated grant date fair value of options vested was $46, and $21 for the three months ended March 31, 2020 and 2021, respectively.

As of March 31, 2021, total unrecognized compensation cost related to all non-vested stock options was $93, which will be amortized over a weighted-average period of 0.43 years.

Restricted Stock Units

The following summarizes the RSU activity for the periods presented:


	Number of awards outstanding	Weighted-average grant date fair value (per share)
Nonvested RSUs as of December 31, 2020	450,614	$	51.58
Granted	113,664	153.90
Vested	(141,707)	48.45
Forfeited or cancelled	(16,696)	63.36
Nonvested RSUs as of March 31, 2021	405,875	$	82.33

As of March 31, 2021, total unrecognized compensation cost related to non-vested RSUs was $31,023, which will be amortized over a weighted-average period of 3.10 years.

Stock-Based Compensation Expense

The Company recognized total stock-based compensation expense as follows:


	Three months ended March 31,
		2020		2021
Cost of revenue		$	175	$	72
Research and development		453		768
Sales and marketing		395		614
General and administrative		1,476		2,936
Total		$	2,499	$	4,390

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. Commitments and Contingencies Operating Leases The Company leases office space under operating lease agreements that expire over the next 5.75 years. See Note 5, “Right-of-Use Asset and Lease Liabilities” to the condensed consolidated financial statements, for additional details on the Company's operating lease commitments. Contractual Obligations On October 25, 2015, the Company entered into an agreement with a telecommunications service provider. The service agreement requires the Company to pay a monthly recurring charge associated with the services received. The service agreement is non-cancellable and contains annual minimum commitments. On August 1, 2020, the Company amended the agreement to require annual minimum commitments of $600 and $300 in 2021 and 2022, respectively. In addition, as of March 31, 2021, the Company has $14,386 in other non-cancellable purchase obligations, consisting of primarily network equipment maintenance and software license contracts, of which $8,519 will be fulfilled within one year. On May 16, 2020, the Company entered into an indemnity agreement with a development company (the “developer”) relating to predevelopment work for approximately 40 acres of vacant land in Raleigh, North Carolina, currently owned by the State of North Carolina (the “State”), upon which the Company intends to construct its office headquarters. The indemnity agreement requires the Company to reimburse the developer one-half of the predevelopment work expenses plus two-thirds of a near future amount to be incurred, to a maximum of $597, if certain conditions are not satisfied. As of March 31, 2021, all of the required conditions were satisfied. On June 15, 2020, the Company signed a Purchase and Sale Agreement (the “Purchase and Sale Agreement”) with the State regarding the proposed sale to Bandwidth of the approximately 40 acres of vacant land located at the southwest quadrant of Reedy Creek Road and Edwards Mill Road in Raleigh, North Carolina (the “Land”). The consideration for the proposed sale of the Land to Bandwidth is $30,000. As part of the purchase and Sale Agreement, the Company is obligated to provide and improve parking facilities for the use by the State of North Carolina which were previously located on the Land. The Purchase and Sale Agreement is subject to due diligence, approvals and other customary closing conditions. Legal Matters The Company is involved as a defendant in various litigation, including but not limited to lawsuits alleging that the Company failed to bill, collect and remit certain taxes and surcharges associated with the provision of 911 services pursuant to applicable laws in various jurisdictions. While the results of these legal proceedings cannot be predicted with certainty, in the opinion of management, the ultimate resolution of these matters will not have a material adverse effect on the Company’s financial position or results of operations.

Employee Benefit Plans

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Employee Benefit Plans

13. Employee Benefit Plans

The Company sponsors a U.S. defined contribution 401(k), which allows eligible U.S.-based employees to defer a portion of their compensation. The Company, at its discretion, may make matching contributions. With the acquisition of Voxbone S.A. on November 1, 2020, the Company assumed sponsorship for Voxbone S.A.’s U.S. defined contribution 401(k). In connection with that acquisition, the Company also assumed sponsorship for a non-U.S. defined contribution plan for which they pay fixed contributions into a separate entity. The Company has no legal or constructive obligations to pay further contributions if the fund does not hold sufficient assets to pay all employees the benefits relating to employee service in the current or prior periods. The contributions are recognized as employee benefit expense when they are due. The Company made matching contributions for the defined contribution plans of $634, and $912 for the three months ended March 31, 2020 and 2021, respectively.

In addition, as a result of the acquisition of Voxbone S.A., the Company assumed sponsorship for Voxbone S.A.’s non-U.S. defined benefit pension plans. The liability recognized in the Other liabilities line item of the balance sheet in respect to these plans is the present value of the defined benefit obligation at the end of the reporting period less the fair value of the plan assets. The defined benefit obligation is calculated annually by an independent actuary using the Projected Unit Credit Method.

The Company reports the service cost component of net periodic benefit cost in the same line item as other compensation costs arising from the services rendered by the employee and records the other components of net periodic benefit cost in other expense, net. Net periodic benefit costs for the non-U.S. defined benefit pension plan were $0 and $104 for the three months ended March 31, 2020 and 2021, respectively.

Pretax amounts for net periodic benefit cost and other amounts for the defined benefit pension plans consisted of the following components:


	Three months ended March 31,
	2021
Service cost	$	103
Interest cost	5
Return on plan assets	(4)
Net periodic pension cost	104



Total recognized in net periodic benefit cost	$	104

Defined benefit cost:
Expected long-term rate of return on plan assets	0.50		%

- Definition

The entire disclosure for retirement benefits.

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+ Details

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	14. Income Taxes At the end of each interim reporting period, the Company determines the income tax provision by using an estimate of the annual effective tax rate, adjusted for discrete items occurring in the quarter. The effective income tax rate reflects the effect of federal and state income taxes and the permanent impacts of differences in book and tax accounting. The Company’s effective tax rate was 72.1% and 5.9% for the three months ended March 31, 2020 and 2021, respectively. The change in tax rate is primarily due to the valuation allowance recorded against U.S. deferred tax assets. The Company continues to maintain a valuation allowance for its U.S. federal and state net deferred tax assets. Judgment is required in determining whether deferred tax assets will be realized in full or in part. Management assesses the available positive and negative evidence on a jurisdictional basis to estimate if deferred tax assets will be recognized and when it is more likely than not that all or some deferred tax assets will not be realized, and a valuation allowance must be established. The Company’s effective tax rate for the three months ended March 31, 2021 is lower than the U.S. federal statutory rate of 21.0% primarily due to the valuation allowance recorded against U.S. deferred tax assets.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Related Parties	3 Months Ended
Related Parties	Mar. 31, 2021
Related Party Transactions [Abstract]
Related Parties	15. Related Parties On April 20, 2015, the Company created a wholly owned subsidiary, Republic, which was incorporated in Delaware. On November 30, 2016, the Company completed a pro-rata distribution of the common stock of Republic to its stockholders of record as of the close of business (the “Spin-Off”). In connection with the Spin-Off on November 30, 2016, the Company and Republic entered into certain agreements in order to govern the ongoing relationships between the two companies after the Spin-Off and to provide for an orderly transition. The agreements include a Transition Services Agreement, Facilities Sharing Agreement, Tax Sharing Agreement, and Master Services Agreement. The equity holders of Bandwidth pre-initial public offering are comprised of substantially the same individuals and entities that are the equity owners of Republic. The Company has determined the equity owners of Republic are related parties of Bandwidth. The Company has certain involvement with Republic via ongoing services arrangements, with these ongoing services arrangements creating a variable interest in Republic. The Company assessed the relationship with Republic under guidance for variable interest entities (“VIE”). Because investors in Republic have disproportionate voting rights, the Company concluded that Republic is a VIE, but Bandwidth is not a primary beneficiary. The Company’s maximum exposure to loss relating to this VIE is limited to amounts due under the service agreements between the Company and Republic. For the three months ended March 31, 2020 and 2021, the Company recorded a reduction of rent expense under the Facilities Sharing Agreement of $96, which is included in general and administrative expenses in the condensed consolidated statements of operations. No amounts were due to the Company under the Facilities Sharing Agreement as of December 31, 2020 and March 31, 2021. The Tax Sharing Agreement governs rights and obligations after the Spin-Off regarding income taxes and other taxes, including tax liabilities and benefits, attributes, returns and contests. There were no amounts outstanding or payable under this agreement as of December 31, 2020 and March 31, 2021. The Master Services Agreement specifies certain wholesale telecommunications services to be provided by the Company. The agreement is cancellable at any time by either party. The Company provided telecommunication services to Republic of $533 and $487 for the three months ended March 31, 2020 and 2021, respectively. The Company recognized such amounts as revenue in the accompanying condensed consolidated statements of operations. As of December 31, 2020 and March 31, 2021, the Company had a receivable of $170 and $153, respectively, under the Master Services Agreement. On March 1, 2019, an amendment to the current Master Services Agreement was executed. Pursuant to the terms of the new agreement, Republic receives reduced pricing on its messaging services, effective April 1, 2019. All other terms and conditions of the existing agreement remain. On June 20, 2019, Republic executed a further amendment to the current Master Services Agreement. Pursuant to the terms of the June 20, 2019 amendment, Republic receives reduced pricing on its outbound voice services effective on June 20, 2019. Subsequent to the expiration of the 180-day IPO blackout window on May 9, 2018, Republic employees that held Bandwidth stock options began exercising their options. Upon exercise, Bandwidth withholds the employee tax amounts due from the proceeds. Bandwidth had collected on behalf of, and remitted withholding tax to, Republic of $308 and $344 for the three months ended March 31, 2020 and 2021, respectively. As of December 31, 2020 and March 31, 2021, the Company had no outstanding amounts due to Republic. On September 30, 2019, the Company entered into a services agreement with Republic. Pursuant to the terms of the new agreement, Republic receives services performed by the Company’s legal department, effective September 30, 2019. The Company is compensated by Republic for these services based on costs incurred by the Company. The Company received net compensation under this agreement of $31 and $6 for the three months ended March 31, 2020 and 2021, respectively, which is included in general and administrative expenses in the condensed consolidated statements of operations. As of December 31, 2020 and March 31, 2021, the Company had a receivable of $2 under this agreement.

Basic and Diluted Loss per Common Share

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

Basic and Diluted Loss per Common Share

16. Basic and Diluted Loss per Common Share

Basic net loss per share is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during the period. The Company is in a net loss position for the three months ended March 31, 2020 and 2021 and therefore diluted shares equals basic shares.

The components of basic and diluted loss per share are as follows:


	Three months ended March 31,
		2020		2021
Earnings per share
Net income (loss)		$	(1,058)	$	(5,316)
Less: net income allocated to participating securities		—		—
Net loss attributable to common stockholders		$	(1,058)	$	(5,316)
Net loss per share:
Basic		$	(0.04)	$	(0.21)
Diluted		$	(0.04)	$	(0.21)














Weighted Average Number of Common Shares Outstanding
Basic		23,563,569		25,015,948




Diluted		23,563,569		25,015,948

The common share equivalents with anti-dilutive effects excluded from the weighted average shares used to calculate net loss per common share for the three months ended March 31, 2020 and 2021 were 1,314,975 and 2,414,442, respectively. For the three months ended March 31, 2020, this consisted of 820,966 stock options and 494,009 nonvested RSUs outstanding. For the three months ended March 31, 2021, this consisted of 196,433 stock options, 405,875 nonvested RSUs outstanding and 1,812,134 from convertible debt conversion.

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	17. Subsequent Events On May 3, 2021, Jeffrey A. Hoffman informed the Company that he has decided to step down as Chief Financial Officer of Bandwidth. Mr. Hoffman’s last day at Bandwidth will be August 31, 2021, and he has offered to work with the Company in an effort to ensure an orderly transition. Mr. Hoffman’s resignation is not due to any disagreement with Bandwidth, its board of directors or management, or any matter relating to the Company’s operations, policies or practices.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Certain information and disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K filed with the SEC on March 1, 2021. The condensed consolidated balance sheet as of December 31, 2020, included herein, was derived from the audited financial statements as of that date, but does not include all disclosures, including certain notes required by GAAP on an annual reporting basis. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full year 2021 or any future period.
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements include the accounts of Bandwidth Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires the Company to make estimates and judgments that affect the amounts reported in these financial statements and accompanying notes. These estimates in the condensed consolidated financial statements include, but are not limited to, allowance for doubtful accounts, reserve for expected credit losses, reserve for sales credits, recoverability of long lived and intangible assets, fair value of acquired intangible assets and goodwill, discount rates used in the valuation of right-of-use assets and lease liabilities, the fair value of the liability and equity components of the Company’s Convertible Notes (as defined herein), estimated period of benefit, valuation allowances on deferred tax assets, certain accrued expenses and contingencies, economic and demographic actuarial assumptions related to pension and other postretirement benefit costs and liabilities, estimated cash flows on asset retirement obligation. Although the Company believes that the estimates it uses are reasonable, due to the inherent uncertainty involved in making these estimates, actual results reported in future periods could differ from those estimates.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents The Company classifies all highly liquid investments with original stated maturities of three months or less from the date of purchase as cash equivalents and all highly liquid investments with original stated maturities of greater than three months from the date of purchase as current marketable securities, with the exception of time deposits which are classified as other investments. Cash deposits are primarily in financial institutions in the United States. However, cash for monthly operating costs of international operations are deposited in banks outside the United States. The Company has a policy of making investments only with commercial institutions that have at least an investment grade credit rating. The Company utilizes money market funds as an investment option and only invests in AAA rated funds. Restricted Cash Restricted cash consists primarily of the holdback amount remaining to be paid to the selling stockholders of Voxbone, employee withholding tax liability and employee benefits contributions not yet remitted. The Company has classified this asset as a short-term asset in order to match the expected period of restriction.
Accounts Receivable	Accounts Receivable and Current Expected Credit Losses Accounts receivable are stated at realizable value, net of allowances, which includes an allowance for doubtful accounts and a reserve for expected credit losses. The allowance for doubtful accounts is based on management’s assessment of the collectability of its customer accounts. The Company regularly reviews the composition of the accounts receivable aging, historical bad debts, changes in payment patterns, customer creditworthiness, current economic trends, and reasonable and supportable forecasts about the future. Relevant risk characteristics include customer size and historical loss patterns. Management has evaluated the expected credit losses related to trade accounts receivable and determined that allowances of approximately $1,203 and $1,218 for uncollectible accounts and customer balances that are disputed were required as of December 31, 2020 and March 31, 2021, respectively. Refer to Note 4, “Financial Statement Components” to these condensed consolidated financial statements, for a rollforward of the components of the allowances as of December 31, 2020 and March 31, 2021. The Company includes unbilled receivables in its accounts receivable balance. Generally, these receivables represent services provided to customers, which will be billed in the next billing cycle. All amounts are considered collectible and billable.
Current Expected Credit Losses	Accounts Receivable and Current Expected Credit Losses Accounts receivable are stated at realizable value, net of allowances, which includes an allowance for doubtful accounts and a reserve for expected credit losses. The allowance for doubtful accounts is based on management’s assessment of the collectability of its customer accounts. The Company regularly reviews the composition of the accounts receivable aging, historical bad debts, changes in payment patterns, customer creditworthiness, current economic trends, and reasonable and supportable forecasts about the future. Relevant risk characteristics include customer size and historical loss patterns. Management has evaluated the expected credit losses related to trade accounts receivable and determined that allowances of approximately $1,203 and $1,218 for uncollectible accounts and customer balances that are disputed were required as of December 31, 2020 and March 31, 2021, respectively. Refer to Note 4, “Financial Statement Components” to these condensed consolidated financial statements, for a rollforward of the components of the allowances as of December 31, 2020 and March 31, 2021. The Company includes unbilled receivables in its accounts receivable balance. Generally, these receivables represent services provided to customers, which will be billed in the next billing cycle. All amounts are considered collectible and billable.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents, other investments and trade accounts receivable. Cash deposits may be in excess of insured limits. The Company believes that the financial institutions that hold its cash deposits are financially sound and, accordingly, minimal credit risk exists with respect to these balances. With regard to customers, credit evaluation and account monitoring procedures are used to minimize the risk of loss. The Company believes that no additional credit risk beyond amounts provided for by the allowance for doubtful accounts are inherent in accounts receivable.
Debt Issuance Costs	Debt Issuance CostsThe Company incurs debt issuance costs associated with obtaining and entering into credit agreements, including the issuances of convertible notes. These costs customarily include non-refundable structuring fees, commitment fees, up-front fees and syndication expenses. The Company has a policy of deferring and amortizing these costs based on the effective interest method over the term of the credit agreements.
Recently Adopted Accounting Standards and Recent Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Standards In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted, including adoption in an interim period. The Company adopted this standard on a prospective basis, which did not have a material impact on the Company’s financial statements. Recent Accounting Pronouncements Not Yet Adopted In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40), which is intended to address issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. For convertible instruments, ASU 2020-06 reduces the number of accounting models for convertible debt instruments and convertible preferred stock, and enhances information transparency by making targeted improvements to the disclosures for convertible instruments and earnings-per-share (EPS) guidance on the basis of feedback from financial statement users. ASU 2020-06 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2021. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company is evaluating the effect of adopting this new accounting guidance on its financial statements and earnings per share calculations, but does not intend to early adopt.

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Schedule of Assets Measured at Fair Value on a Recurring Basis

The following table summarizes the assets measured at fair value as of December 31, 2020 and March 31, 2021:


				Fair value measurements on a recurring basis December 31, 2020
	Level 1	Level 2	Level 3	Total
Financial assets:
Cash and cash equivalents:
Money market account				$	57,517	$	—	$	—	$	57,517








Other investments:
Time deposits				40,000		—		—		40,000

Total financial assets				$	97,517	$	—	$	—	$	97,517


				Fair value measurements on a recurring basis March 31, 2021
	Level 1	Level 2	Level 3			Total
Financial assets:
Cash and cash equivalents:
Money market account				$	283,504		$	—	$	—	$	283,504
Time deposits				15,000			—		—		15,000



Total included in cash and cash equivalents				298,504			—		—		298,504




Other investments:
Time deposits				10,000			—		—		10,000

Total financial assets				$	308,504		$	—	$	—	$	308,504

Financial Statement Components (Tables)

3 Months Ended

Mar. 31, 2021

Financial Statement Components [Abstract]

Schedule of Accounts Receivable, net, and Allowance for Doubtful Accounts

Accounts receivable, net of allowances consist of the following:


	As of December 31,		As of March 31,
	2020		2021
Trade accounts receivable	$	26,504	$	22,591
Unbilled accounts receivable	27,692		28,490
Allowance for doubtful accounts and reserve for expected credit losses	(1,203)		(1,218)
Other accounts receivable	2,250		1,595
Total accounts receivable, net	$	55,243	$	51,458

Components of allowance for doubtful accounts and reserve for expected credit losses are as follows:


	Three months ended March 31,
		2020		2021
Allowance for doubtful accounts:
Balance, beginning of period		$	(769)	$	(1,203)
Charged to bad debt expense		(189)		(48)
Deductions (1)		75		10
Impact of foreign currency translation		—		23



Balance, end of period		$	(883)	$	(1,218)

________________________

(1) Write off of uncollectible accounts after all collection efforts have been exhausted.

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:


	As of December 31,		As of March 31,
	2020		2021
Accrued expense	$	31,549	$	32,476
Accrued compensation and benefits	19,534		11,531
Accrued sales, use, VAT and telecommunications related taxes	9,142		9,114

Other accrued expenses	2,657		2,588
Current portion of finance lease	183		175
Total accrued expenses and other current liabilities	$	63,065	$	55,884

Right-of-Use Asset and Lease Liabilities (Tables)

3 Months Ended

Mar. 31, 2021

Leases [Abstract]

Schedule of Future Minimum Lease Receipts for Operating Lease

Future minimum sub-lease receipts required under the non-cancellable lease are as follows:


	As of March 31,
	2021
2021 (remaining)	$	345
2022	249



	$	594

Components of Lease Expense

The components of lease expense recorded in the condensed consolidated statement of operations were as follows:


	Three months ended March 31,
		2020		2021
Operating lease cost		$	1,461	$	1,614
Finance lease cost:
Depreciation of assets		—		47



Sublease income (1)		(96)		(96)
Total net lease cost		$	1,365	$	1,565

________________________

(1) See Note 15, “Related Parties” to these condensed consolidated financial statements, for additional details on sublease income.

Supplemental cash flow and other information related to leases was as follows:


	Three months ended March 31,
		2020			2021
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases		$	1,285		$	1,371

Financing cash flows from finance leases		—			44
		$	1,285		$	1,415

Weighted average remaining lease term (in years)
Operating leases		4.11			3.53
Finance leases		—			2.86

Weighted average discount rate
Operating leases		4.99		%	4.81		%
Finance leases		—		%	4.00		%

Supplemental Balance Sheet Lease Information

Supplemental balance sheet information related to leases was as follows:


		As of December 31,		As of March 31,
Leases	Classification	2020		2021
Assets:
Operating lease assets	Operating right-of-use asset, net (1)	$	19,491	$	18,008
Finance lease assets	Property and equipment, net (2)	464		428
Total leased assets		$	19,955	$	18,436

Liabilities:
Current
Operating	Operating lease liability, current	$	5,515	$	5,594
Finance	Accrued expenses and other current liabilities	183		175
Non-current
Operating	Operating lease liability, net of current portion	17,202		15,609
Finance	Other liabilities	282		258
Total lease liabilities		$	23,182	$	21,636

________________________

(1) Operating lease assets are recorded net of accumulated amortization of $9,083 and $10,435 as of December 31, 2020 and March 31, 2021, respectively.

(2) Finance lease assets are recorded net of accumulated depreciation of $28 and $74 as of December 31, 2020 and March 31, 2021, respectively.

Schedule of Maturities of Operating Lease Liabilities

Maturities of operating lease liabilities were as follows:


	As of March 31,
	2021
2021 (remaining)	$	4,756
2022	6,736
2023	6,593
2024	2,670
2025	1,648

Thereafter	718
Total lease payments	23,121
Less: imputed interest	(1,918)

Total lease obligations	21,203
Less: current obligations	(5,594)
Long-term lease obligations	$	15,609

Schedule of Maturities of Finance Lease Liabilities

Maturities of financing lease liabilities were as follows:


	As of March 31,
	2021
2021 (remaining)	$	147
2022	148
2023	97
2024	61
2025	4


Total lease payments	457
Less: imputed interest	(24)

Total lease obligations	433
Less: current obligations	(175)
Long-term lease obligations	$	258

Property and Equipment (Tables)

3 Months Ended

Mar. 31, 2021

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment, Net

Property and equipment, net consisted of the following:


	As of December 31,		As of March 31,
	2020		2021
Furniture and fixtures	$	2,341	$	2,348
Computer and office equipment	4,077		4,190
Telecommunications equipment	60,651		61,753
Leasehold improvements	6,285		6,280
Software	3,901		4,877
Internal-use software development	19,968		20,884
Automobile	502		512
Total cost	97,725		100,844
Less—accumulated depreciation	(46,080)		(50,184)
Total property and equipment, net	$	51,645	$	50,660

Schedule of Depreciation Expense

The Company recognized depreciation expense, which includes amortization of capitalized software development costs, as follows:


	Three months ended March 31,
		2020		2021
Cost of revenue		$	2,334	$	3,033
Research and development		115		240
Sales and marketing		29		29
General and administrative		690		874
Total depreciation expense		$	3,168	$	4,176

Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite Lived Intangible Assets

Intangible assets, net consisted of the following as of December 31, 2020:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,111)	$	5,285	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquistion and other intangible assets	15,093		(9,044)		6,049

Voxbone acquistion:
Customer relationships	156,559		(1,739)		154,820		15
Developed technology	88,664		(1,478)		87,186		10
Total Voxbone acquisition	245,223		(3,217)		242,006

Total intangible assets, net	$	260,316	$	(12,261)	$	248,055

Intangible assets, net consisted of the following as of March 31, 2021:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,241)	$	5,155	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquisition and other intangible assets	15,093		(9,174)		5,919

Voxbone acquisition:
Customer relationships	149,764		(4,161)		145,603		15
Developed technology	84,816		(3,534)		81,282		10
Total Voxbone acquisition	234,580		(7,695)		226,885

Total intangibles, net	$	249,673	$	(16,869)	$	232,804

Schedule of Infinite Lived Intangible Assets

Intangible assets, net consisted of the following as of December 31, 2020:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,111)	$	5,285	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquistion and other intangible assets	15,093		(9,044)		6,049

Voxbone acquistion:
Customer relationships	156,559		(1,739)		154,820		15
Developed technology	88,664		(1,478)		87,186		10
Total Voxbone acquisition	245,223		(3,217)		242,006

Total intangible assets, net	$	260,316	$	(12,261)	$	248,055

Intangible assets, net consisted of the following as of March 31, 2021:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,241)	$	5,155	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquisition and other intangible assets	15,093		(9,174)		5,919

Voxbone acquisition:
Customer relationships	149,764		(4,161)		145,603		15
Developed technology	84,816		(3,534)		81,282		10
Total Voxbone acquisition	234,580		(7,695)		226,885

Total intangibles, net	$	249,673	$	(16,869)	$	232,804

Schedule of Future Estimated Amortization Expense

Future estimated amortization expense for definite lived intangible assets is as follows:


	As of March 31,
	2021
2021 (remaining)	$	14,239
2022	18,986
2023	18,986
2024	18,986
2025	18,986


Thereafter	141,857
	$	232,040

Debt (Tables)

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Net Carrying Amount of Liability and Equity Component of Notes

The net carrying amount of the liability components of the 2026 and 2028 Convertible Notes were as follows:


	As of December 31,		As of March 31,
	2020		2021
2026 Convertible Notes:
Principal	$	400,000	$	400,000
Unamortized discount	(110,546)		(106,036)
Unamortized debt issuance costs	(7,258)		(6,962)
2026 Convertible Notes net carrying amount	282,196		287,002

2028 Convertible Notes:
Principal	—		250,000
Unamortized discount	—		(66,575)
Unamortized debt issuance costs	—		(5,579)
2028 Convertible Notes net carrying amount	—		177,846
Total net carrying amount	$	282,196	$	464,848

The net carrying amount of the equity components of the 2026 and 2028 Convertible Notes were as follows:


	As of December 31,		As of March 31,
	2020		2021
2026 Convertible Notes:
Proceeds allocated to the conversion options (debt discount)	$	125,152	$	125,152
Issuance costs	(3,742)		(3,742)
2026 Convertible Notes net carrying amount	121,410		121,410

2028 Convertible Notes:
Proceeds allocated to the conversion options (debt discount)	—		66,908
Issuance costs	—		(2,049)
2028 Convertible Notes net carrying amount	—		64,859
Total net carrying amount	$	121,410	$	186,269

Interest Income and Interest Expense Disclosure

The following table sets forth the interest expense recognized related to the 2026 and 2028 Convertible Notes:


	Three months ended March 31,
		2020		2021
2026 Convertible Notes:
Contractual interest expense		$	96	$	250
Amortization of debt discount		1,629		4,510
Amortization of debt issuance costs		106		296
Total interest expense related to the 2026 Convertible Notes		1,831		5,056

2028 Convertible Notes:
Contractual interest expense		—		52
Amortization of debt discount		—		333
Amortization of debt issuance costs		—		28
Total interest expense related to the 2028 Convertible Notes		—		413
Total interest expense		$	1,831	$	5,469

Segment and Geographic Information (Tables)

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment


	Three months ended March 31,
		2020		2021
CPaaS
Revenue		$	59,121	$	100,146
Cost of revenue		31,892		53,681
Gross profit		$	27,229	$	46,465
Other
Revenue		$	9,397	$	13,333
Cost of revenue		4,467		7,647
Gross profit		$	4,930	$	5,686
Consolidated
Revenue		$	68,518	$	113,479
Cost of revenue		36,359		61,328
Gross profit		$	32,159	$	52,151

Schedule of Revenue by Geographical Area

The Company generates its revenue primarily in the United States. Revenue by geographic area is detailed in the table below (which is determined based on the customer billing address):


	Three months ended March 31,
		2020		2021
CPaaS
United States		$	57,398	$	88,862
International		1,723		11,284
Total		$	59,121	$	100,146

Other
United States		$	9,125	$	11,936
International		272		1,397
Total		$	9,397	$	13,333

Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2021

Equity [Abstract]

Schedule of Reserved Shares of Common Stock for Issuance

The Company had reserved shares of Class A common stock for issuance under stock-based award agreements as follows:


	As of December 31,	As of March 31,
	2020	2021
Stock options issued and outstanding	255,000	196,433
Nonvested restricted stock units issued and outstanding	450,614	405,875
Stock-based awards available for grant under the 2017 Plan	2,020,342	3,044,024
	2,725,956	3,646,332

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=65877616&loc=d3e177068-122764

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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+ Details

Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Share-based Payment Arrangement [Abstract]

Summary of Stock Option Activity

The following summarizes the stock option activity for the periods presented:


	Number of options outstanding	Weighted- average exercise price (per share)		Weighted- average remaining contract life (in years)	Aggregate intrinsic value (in thousands)
Outstanding as of December 31, 2020	255,000	$	10.82	4.42	$	36,426
Granted	—	—
Exercised	(57,817)	13.02			7,697
Forfeited or cancelled	(750)	9.57
Outstanding as of March 31, 2021	196,433	$	10.18	4.18	$	22,897

Options vested and exercisable at March 31, 2021	170,100	$	8.95	3.83	$	20,035
Options vested and expected to vest as of March 31, 2021	195,810	$	10.16	4.18	$	22,828

Summary of Restricted Stock Unit Activity

The following summarizes the RSU activity for the periods presented:


	Number of awards outstanding	Weighted-average grant date fair value (per share)
Nonvested RSUs as of December 31, 2020	450,614	$	51.58
Granted	113,664	153.90
Vested	(141,707)	48.45
Forfeited or cancelled	(16,696)	63.36
Nonvested RSUs as of March 31, 2021	405,875	$	82.33

Schedule of Stock-Based Compensation Expense

The Company recognized total stock-based compensation expense as follows:


	Three months ended March 31,
		2020		2021
Cost of revenue		$	175	$	72
Research and development		453		768
Sales and marketing		395		614
General and administrative		1,476		2,936
Total		$	2,499	$	4,390

Employee Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Summary of Accumulated Benefit Obligation in Excess of Plan Assets

Pretax amounts for net periodic benefit cost and other amounts for the defined benefit pension plans consisted of the following components:


	Three months ended March 31,
	2021
Service cost	$	103
Interest cost	5
Return on plan assets	(4)
Net periodic pension cost	104



Total recognized in net periodic benefit cost	$	104

Defined benefit cost:
Expected long-term rate of return on plan assets	0.50		%

Basic and Diluted Loss per Common Share (Tables)

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The components of basic and diluted loss per share are as follows:


	Three months ended March 31,
		2020		2021
Earnings per share
Net income (loss)		$	(1,058)	$	(5,316)
Less: net income allocated to participating securities		—		—
Net loss attributable to common stockholders		$	(1,058)	$	(5,316)
Net loss per share:
Basic		$	(0.04)	$	(0.21)
Diluted		$	(0.04)	$	(0.21)














Weighted Average Number of Common Shares Outstanding
Basic		23,563,569		25,015,948




Diluted		23,563,569		25,015,948

Organization and Description of Business (Details) € in Millions, $ in Millions			3 Months Ended
	Nov. 02, 2020 USD ($)	Nov. 02, 2020 EUR (€)	Mar. 31, 2021 segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments			2
Number of reportable segments			2
Voxbone S.A
Business Acquisition [Line Items]
Total purchase consideration \| €		€ 446
Fair value of cash paid	$ 400	338
Voxbone S.A \| Common stock
Business Acquisition [Line Items]
Fair value of Bandwidth common stock issued	$ 128	€ 108

Summary of Significant Accounting Policies - Cash and Cash Equivalents and Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Allowance for doubtful accounts	$ 1,218	$ 1,203
Unbilled accounts receivable	$ 28,490	$ 27,692

Summary of Significant Accounting Policies - Accounts Receivable and Current Expected Credit Losses and Concentration of Credit Risk and Deferred Revenue and Customer Deposits (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Customer One \| Accounts Receivable
Concentration Risk [Line Items]
Concentration risk percentage	12.00%	11.00%

Fair Value Measurements - Assets Measured at Fair Value (Details) - Fair value measurements on a recurring basis - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 298,504
Money market account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	283,504	$ 57,517
Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	15,000
Total other investments	10,000	40,000
Financial assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	308,504	97,517
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	298,504
Level 1 \| Money market account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	283,504	57,517
Level 1 \| Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	15,000
Total other investments	10,000	40,000
Level 1 \| Financial assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	308,504	97,517
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0
Level 2 \| Money market account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Level 2 \| Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0
Total other investments	0	0
Level 2 \| Financial assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0
Level 3 \| Money market account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Level 3 \| Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0
Total other investments	0	0
Level 3 \| Financial assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 0	$ 0

Fair Value Measurements - Additional Information (Details) - Convertible notes $ in Thousands	Mar. 31, 2021 USD ($)
0.25% Convertible senior notes due 2026
Debt Instrument [Line Items]
Fair value	$ 609,698
0.50% Convertible senior notes due 2028
Debt Instrument [Line Items]
Fair value	$ 245,206

Financial Statement Components - Accounts Receivable, Net of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financial Statement Components [Abstract]
Trade accounts receivable	$ 22,591	$ 26,504
Unbilled accounts receivable	28,490	27,692
Allowance for doubtful accounts and reserve for expected credit losses	(1,218)	(1,203)
Other accounts receivable	1,595	2,250
Total accounts receivable, net	$ 51,458	$ 55,243

Financial Statement Components - Allowance For Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	$ (1,203)	$ (769)
Charged to bad debt expense	(48)	(189)
Deductions	10	75
Impact of foreign currency translation	23	0
Balance, end of period	$ (1,218)	$ (883)

Financial Statement Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financial Statement Components [Abstract]
Accrued expense	$ 32,476	$ 31,549
Accrued compensation and benefits	11,531	19,534
Accrued sales, use, VAT and telecommunications related taxes	9,114	9,142
Other accrued expenses	2,588	2,657
Current portion of finance lease	175	183
Total accrued expenses and other current liabilities	$ 55,884	$ 63,065

Right-of-Use Asset and Lease Liabilities - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($) ft² segment	Mar. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Office space (in square foot) \| ft²	17,073
Option to extend, term	5 years
Number of leases with early-termination option \| segment	1
Short-term operating lease expense \| $	$ 345	$ 0
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	8 months
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	5 years 9 months

Right-of-Use Asset and Lease Liabilities - Future Minimum Sub-lease Receipts (Details) $ in Thousands	Mar. 31, 2021 USD ($)
Leases [Abstract]
2021 (remaining)	$ 345
2022	249
Total	$ 594

Right-of-Use Asset and Lease Liabilities - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease cost	$ 1,614	$ 1,461
Depreciation of assets	47	0
Sublease income	(96)	(96)
Total net lease cost	$ 1,565	$ 1,365

Right-of-Use Asset and Lease Liabilities - Supplemental Balance Sheet Lease Information (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets:
Operating lease assets	$ 18,008	$ 19,491
Finance lease assets	428	464
Total leased assets	18,436	19,955
Current
Operating	5,594	5,515
Finance	175	183
Non-current
Long-term lease obligations	15,609	17,202
Long-term lease obligations	258	282
Total lease obligations	21,636	23,182
Accumulated amortization	10,435	9,083
Accumulated depreciation of assets under finance leases	$ 74	$ 28
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent

Right-of-Use Asset and Lease Liabilities - Supplemental Cash Flow and Other Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 1,371	$ 1,285
Financing cash flows from finance leases	44	0
Lease liabilities	$ 1,415	$ 1,285
Weighted average remaining lease term (in years)
Operating leases	3 years 6 months 10 days		4 years 1 month 9 days
Finance leases	2 years 10 months 9 days		0 years
Weighted average discount rate
Operating leases	4.81%	4.99%
Finance leases	4.00%	0.00%

Right-of-Use Asset and Lease Liabilities - Schedule of Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
2021 (remaining)	$ 4,756
2022	6,736
2023	6,593
2024	2,670
2025	1,648
Thereafter	718
Total lease payments	23,121
Less: imputed interest	(1,918)
Total lease obligations	21,203
Less: current obligations	(5,594)	$ (5,515)
Long-term lease obligations	$ 15,609	$ 17,202

Right-of-Use Asset and Lease Liabilities - Schedule of Maturities of Finance Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
2021 (remaining)	$ 147
2022	148
2023	97
2024	61
2025	4
Total lease payments	457
Less: imputed interest	(24)
Total lease obligations	433
Less: current obligations	(175)	$ (183)
Long-term lease obligations	$ 258	$ 282

Property and Equipment - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total cost	$ 100,844	$ 97,725
Less—accumulated depreciation	(50,184)	(46,080)
Property and equipment, net	50,660	51,645
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total cost	2,348	2,341
Computer and office equipment
Property, Plant and Equipment [Line Items]
Total cost	4,190	4,077
Telecommunications equipment
Property, Plant and Equipment [Line Items]
Total cost	61,753	60,651
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total cost	6,280	6,285
Software
Property, Plant and Equipment [Line Items]
Total cost	4,877	3,901
Internal-use software development
Property, Plant and Equipment [Line Items]
Total cost	20,884	19,968
Automobile
Property, Plant and Equipment [Line Items]
Total cost	$ 512	$ 502

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Capitalized software development costs, additions	$ 1,103	$ 790
Amortization of capitalized software development costs	420	$ 582
Capitalized implementation costs related to cloud computing arrangements	533
Cost of assets under finance leases	502
Accumulated depreciation of assets under finance leases	74		$ 28
Prepaid expenses and other current assets
Property, Plant and Equipment [Line Items]
Capitalized implementation costs related to cloud computing arrangements	140
Other long-term assets
Property, Plant and Equipment [Line Items]
Capitalized implementation costs related to cloud computing arrangements	$ 393

Property and Equipment - Depreciation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Depreciation Expense [Line Items]
Total depreciation expense	$ 4,176	$ 3,168
Cost of revenue
Depreciation Expense [Line Items]
Total depreciation expense	3,033	2,334
Research and development
Depreciation Expense [Line Items]
Total depreciation expense	240	115
Sales and marketing
Depreciation Expense [Line Items]
Total depreciation expense	29	29
General and administrative expenses
Depreciation Expense [Line Items]
Total depreciation expense	$ 874	$ 690

Intangible Assets - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Dash acquisition and other intangibles:
Accumulated Amortization	$ (16,869)	$ (12,261)
Finite-lived intangible assets, net	232,040
Gross Amount	249,673	260,316
Net Carrying Value	232,804	248,055
Dash
Dash acquisition and other intangibles:
Accumulated Amortization	(9,174)	(9,044)
Gross Amount	15,093	15,093
Net Carrying Value	5,919	6,049
Dash \| Licenses
Dash acquisition and other intangibles:
Licenses, indefinite lived	764	764
Dash \| Customer relationships
Dash acquisition and other intangibles:
Finite-lived intangible assets, gross	10,396	10,396
Accumulated Amortization	(5,241)	(5,111)
Finite-lived intangible assets, net	$ 5,155	$ 5,285
Amortization Period	20 years	20 years
Dash \| Other, definite lived
Dash acquisition and other intangibles:
Finite-lived intangible assets, gross	$ 3,933	$ 3,933
Accumulated Amortization	(3,933)	(3,933)
Finite-lived intangible assets, net	$ 0	$ 0
Dash \| Other, definite lived \| Minimum
Dash acquisition and other intangibles:
Amortization Period	2 years	2 years
Dash \| Other, definite lived \| Maximum
Dash acquisition and other intangibles:
Amortization Period	7 years	7 years
Voxbone S.A
Dash acquisition and other intangibles:
Accumulated Amortization	$ (7,695)	$ (3,217)
Gross Amount	234,580	245,223
Net Carrying Value	226,885	242,006
Voxbone S.A \| Customer relationships
Dash acquisition and other intangibles:
Finite-lived intangible assets, gross	149,764	156,559
Accumulated Amortization	(4,161)	(1,739)
Finite-lived intangible assets, net	$ 145,603	$ 154,820
Amortization Period	15 years	15 years
Voxbone S.A \| Developed technology
Dash acquisition and other intangibles:
Finite-lived intangible assets, gross	$ 84,816	$ 88,664
Accumulated Amortization	(3,534)	(1,478)
Finite-lived intangible assets, net	$ 81,282	$ 87,186
Amortization Period	10 years	10 years

Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 4,867	$ 130
Weighted average useful life	13 years

Intangible Assets - Future Estimated Amortization Expense (Details) $ in Thousands	Mar. 31, 2021 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2021 (remaining)	$ 14,239
2022	18,986
2023	18,986
2024	18,986
2025	18,986
Thereafter	141,857
Finite-lived intangible assets, net	$ 232,040

Debt - Revolving Loan (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Outstanding unamortized loan fees		$ 83,000
Long-term debt	$ 464,848,000	282,196,000
Credit Facility
Debt Instrument [Line Items]
Long-term debt	0	0
Borrowing capacity	25,000,000
Prepaid expenses and other current assets
Debt Instrument [Line Items]
Outstanding unamortized loan fees	$ 64,000	74,000
Noncurrent assets
Debt Instrument [Line Items]
Outstanding unamortized loan fees		$ 9,000

Debt - 2026 Convertible Notes (Details)		3 Months Ended
Debt - 2026 Convertible Notes (Details)	Feb. 28, 2020 USD ($) d $ / shares	Mar. 31, 2021 USD ($) d $ / shares	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) $ / shares
Class A voting common stock
Debt Instrument [Line Items]
Common stock, par value (in usd per share) \| $ / shares		$ 0.001		$ 0.001
2026 Convertible Notes
Debt Instrument [Line Items]
Principal		$ 400,000,000		$ 400,000,000
Cash redemption price, percent	100.00%
Conversion option		125,152,000	$ 125,152,000
Issuance costs			$ 3,742,000
2026 Convertible Notes \| Class A voting common stock
Debt Instrument [Line Items]
Common stock, par value (in usd per share) \| $ / shares	$ 0.001
2026 Convertible Notes \| Convertible notes
Debt Instrument [Line Items]
Principal	$ 400,000,000
Stated rate	0.25%
Total net proceeds	$ 344,722,000
Conversion price (usd per share) \| $ / shares	$ 91.03
Conversion option	$ 125,160,000
Effective interest rate	6.763%
Carrying amount of equity component	$ 57,491,000
Annual effective interest rate	6.807%
Issuance costs attributable to the liability component	$ 8,217,000
Issuance costs	$ 3,742,000	$ 3,742,000
2026 Convertible Notes \| Convertible notes \| Conversion option 1
Debt Instrument [Line Items]
Trading days \| d	20	20
Consecutive trading days \| d	30	30
2026 Convertible Notes \| Convertible notes \| Conversion option 2
Debt Instrument [Line Items]
Consecutive trading days \| d	10
Consecutive business days \| d	5
2026 Convertible Notes \| Convertible notes \| Class A voting common stock
Debt Instrument [Line Items]
Conversion ratio	10.9857
2026 Convertible Notes \| Convertible notes \| Class A voting common stock \| Conversion option 1
Debt Instrument [Line Items]
Stock price trigger percent	130.00%	130.00%
2026 Convertible Notes \| Convertible notes \| Class A voting common stock \| Conversion option 2
Debt Instrument [Line Items]
Stock price trigger percent	98.00%

Debt - 2028 Convertible Notes (Details)		3 Months Ended
Debt - 2028 Convertible Notes (Details)	Mar. 16, 2021 USD ($) d $ / shares	Mar. 31, 2021 USD ($) $ / shares	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) $ / shares
Class A voting common stock
Debt Instrument [Line Items]
Common stock, par value (in usd per share) \| $ / shares		$ 0.001		$ 0.001
2028 Convertible Notes
Debt Instrument [Line Items]
Principal		$ 250,000,000		$ 0
Conversion option		66,908,000	$ 0
Issuance costs			$ 0
2028 Convertible Notes \| Class A voting common stock
Debt Instrument [Line Items]
Common stock, par value (in usd per share) \| $ / shares	$ 0.001
2028 Convertible Notes \| Convertible notes
Debt Instrument [Line Items]
Principal	$ 250,000,000
Stated rate	0.50%
Total net proceeds	$ 216,845,000
Conversion ratio	5.5781
Conversion price (usd per share) \| $ / shares	$ 179.27
Cash redemption price, percent	100.00%
Conversion option	$ 66,908,000
Effective interest rate	5.125%
Carrying amount of equity component	$ 39,359,000
Annual effective interest rate	4.966%
Issuance costs attributable to the liability component	$ 5,607,000
Issuance costs	$ 2,049,000	$ 2,049,000
2028 Convertible Notes \| Convertible notes \| Conversion option 1
Debt Instrument [Line Items]
Trading days \| d	20
Consecutive trading days \| d	30
2028 Convertible Notes \| Convertible notes \| Conversion option 1 \| Class A voting common stock
Debt Instrument [Line Items]
Stock price trigger percent	130.00%
2028 Convertible Notes \| Convertible notes \| Conversion option 2
Debt Instrument [Line Items]
Consecutive trading days \| d	10
Consecutive business days \| d	5
2028 Convertible Notes \| Convertible notes \| Conversion option 2 \| Class A voting common stock
Debt Instrument [Line Items]
Stock price trigger percent	98.00%

Debt - Schedule of Debt (Details) - USD ($)	3 Months Ended
Debt - Schedule of Debt (Details) - USD ($)	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Debt Instrument [Line Items]
Total net carrying amount	$ 464,848,000		$ 282,196,000
Total net carrying amount	186,269,000	$ 121,410,000
2026 Convertible Notes
Debt Instrument [Line Items]
Principal	400,000,000		400,000,000
Unamortized discount	(106,036,000)		(110,546,000)
Unamortized debt issuance costs	(6,962,000)		(7,258,000)
Total net carrying amount	287,002,000		282,196,000
Proceeds allocated to the conversion options (debt discount)	125,152,000	125,152,000
Issuance costs		(3,742,000)
Total net carrying amount	121,410,000	121,410,000
2028 Convertible Notes
Debt Instrument [Line Items]
Principal	250,000,000		0
Unamortized discount	(66,575,000)		0
Unamortized debt issuance costs	(5,579,000)		0
Total net carrying amount	177,846,000		$ 0
Proceeds allocated to the conversion options (debt discount)	66,908,000	0
Issuance costs		0
Total net carrying amount	$ 64,859,000	$ 0

Debt - Interest Income and Interest Expense Disclosure (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Debt Instrument [Line Items]
Total interest expense	$ 5,469	$ 1,831
2026 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	250	96
Amortization of debt discount	4,510	1,629
Amortization of debt issuance costs	296	106
Total interest expense	5,056	1,831
2028 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	52	0
Amortization of debt discount	333	0
Amortization of debt issuance costs	28	0
Total interest expense	$ 413	$ 0

Debt - Convertible Senior Notes and Capped Call Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 16, 2021	Feb. 28, 2020
Debt Instrument [Line Items]
Net cost of capped call purchase	$ 25,500	$ 43,320
Class A voting common stock
Debt Instrument [Line Items]
Capped call shares (in shares)	1,917,472	4,394,276
0.25% Convertible senior notes due 2026 \| Convertible notes
Debt Instrument [Line Items]
Initial conversion strike price (usd per share)		$ 91.03
Initial cap price (usd per share)		$ 137.40
0.50% Convertible senior notes due 2028 \| Convertible notes
Debt Instrument [Line Items]
Initial conversion strike price (usd per share)	$ 179.27
Initial cap price (usd per share)	$ 260.76

Segment and Geographic Information - Reconciliation of Segment Profit (Loss) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($) segment	Mar. 31, 2020 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| segment	2
Segment Reporting Information [Line Items]
Revenue	$ 113,479	$ 68,518
Cost of revenue	61,328	36,359
Gross profit	52,151	32,159
CPaaS
Segment Reporting Information [Line Items]
Revenue	100,146	59,121
Cost of revenue	53,681	31,892
Gross profit	46,465	27,229
Other
Segment Reporting Information [Line Items]
Revenue	13,333	9,397
Cost of revenue	7,647	4,467
Gross profit	$ 5,686	$ 4,930

- Definition

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

+ References

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+ Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Segment and Geographic Information - Reconciliation of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Revenues from External Customers and Long-Lived Assets [Line Items]
Assets	$ 1,070,349		$ 890,608
Revenue	113,479	$ 68,518
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Assets	10,537		$ 11,249
CPaaS
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	100,146	59,121
CPaaS \| United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	88,862	57,398
CPaaS \| International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	11,284	1,723
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	13,333	9,397
Other \| United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	11,936	9,125
Other \| International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,397	$ 272

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Stockholders' Equity - Preferred Stock (Details) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Equity [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares issued (in shares)	0	0
Preferred A stock, shares outstanding (in shares)	0	0

Stockholders' Equity - Common Stock (Details)	Mar. 31, 2021 vote $ / shares shares	Dec. 31, 2020 vote $ / shares shares
Class A voting common stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, par value (in usd per share) \| $ / shares	$ 0.001	$ 0.001
Common stock voting rights \| vote	1	1
Common stock, shares issued (in shares)	22,873,604	22,413,004
Common stock, shares outstanding (in shares)	22,873,604	22,413,004
Class B voting common stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, par value (in usd per share) \| $ / shares	$ 0.001	$ 0.001
Common stock voting rights \| vote	10	10
Common stock, shares issued (in shares)	2,215,170	2,496,125
Common stock, shares outstanding (in shares)	2,215,170	2,496,125

Stockholders' Equity - Reserved Shares of Common Stock for Issuance (Details) - shares	Mar. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	3,646,332	2,725,956
Stock options issued and outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	196,433	255,000
Nonvested restricted stock units issued and outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	405,875	450,614
Stock-based awards available for grant under the 2017 Plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	3,044,024	2,020,342

Stock Based Compensation - Additional Information (Details) - USD ($) $ in Thousands				3 Months Ended
	Jan. 01, 2021	Jan. 01, 2018	Nov. 09, 2017	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)				3,646,332		2,725,956
Estimated grant date fair value of options vested				$ 21	$ 46
Unrecognized cost for stock based compensation				$ 93
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options, granted (in shares)				0	0
Unrecognized cost for stock based compensation, period for recognition (in years)				5 months 4 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)				405,875		450,614
Unrecognized cost for stock based compensation, period for recognition (in years)				3 years 1 month 6 days
Unrecognized compensation cost related to non-vested RSUs				$ 31,023
2010 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)				0
2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)			1,050,000
Common stock reserved for future issuance, percent increase		5.00%
Increase in shares available for grant (in shares)	1,120,650
2017 Plan \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			4 years
Contractual life (in years)			10 years
2017 Plan \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Service period			4 years
2017 Plan \| Restricted Stock Units (RSUs) \| Non-employee Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			25.00%
2017 Plan \| Restricted Stock Units (RSUs) \| Executives
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			4 years
2017 Plan \| Restricted Stock Units (RSUs) \| Executives \| Year one vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			50.00%
2017 Plan \| Restricted Stock Units (RSUs) \| Executives \| First quarter vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			12.50%
2017 Plan \| Restricted Stock Units (RSUs) \| Executives \| Second quarter vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			12.50%
2017 Plan \| Restricted Stock Units (RSUs) \| Executives \| Third quarter vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			12.50%
2017 Plan \| Restricted Stock Units (RSUs) \| Executives \| First quarter vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			12.50%
2017 Plan \| Restricted Stock Units (RSUs) \| Executives \| Year two, three and four vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			50.00%

Stock Based Compensation - Stock Option Activity (Details) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Number of options outstanding
Number of options outstanding, beginning balance (in shares)	255,000
Number of options, granted (in shares)	0		0
Number of options exercised (in shares)	(57,817)
Number of options, forfeited or cancelled (in shares)	(750)
Number of options outstanding, ending balance (in shares)	196,433	255,000
Options vested and exercisable (in shares)	170,100
Options vested and expected to vest (in shares)	195,810
Weighted- average exercise price (per share)
Weighted-average exercise price, beginning balance (in usd per share)	$ 10.82
Weighted-average exercise price, granted (in usd per share)	0
Weighted-average exercise price, exercised (in usd per share)	13.02
Weighted-average exercise price, forfeited or cancelled (in usd per share)	9.57
Weighted-average exercise price, ending balance (in usd per share)	10.18	$ 10.82
Weighted-average exercise price, options vested and exercisable (in usd per share)	8.95
Weighted average exercise price, options vested and expected to vest (in usd per share)	$ 10.16
Weighted- average remaining contract life (in years)
Weighted-average remaining contract life, options outstanding (in years)	4 years 2 months 4 days		4 years 5 months 1 day
Weighted-average remaining contract life, options vested and exercisable (in years)	3 years 9 months 29 days
Weighted average remaining contract life, options vested and expected to vest	4 years 2 months 4 days
Aggregate intrinsic value (in thousands)
Aggregate intrinsic value, options outstanding	$ 22,897	$ 36,426
Aggregate intrinsic value, options exercised	7,697
Aggregate intrinsic value, options vested and exercisable	20,035
Aggregate intrinsic value, options vested and expected to vest	$ 22,828

Stock Based Compensation - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2021 $ / shares shares
Number of awards outstanding
Number of nonvested RSUs outstanding, beginning balance (in shares) \| shares	450,614
Number of nonvested RSUs, granted (in shares) \| shares	113,664
Number of nonvested RSUs, vested (in shares) \| shares	(141,707)
Number of nonvested RSUs, forfeited or cancelled (in shares) \| shares	(16,696)
Number of nonvested RSUs outstanding, ending balance (in shares) \| shares	405,875
Weighted-average grant date fair value (per share)
Weighted-average grant date fair value, beginning balance (in usd per share) \| $ / shares	$ 51.58
Weighted average grant-date fair value of nonvested RSUs, granted (in usd per share) \| $ / shares	153.90
Weighted-average grant date fair value of nonvested RSUs, vested (in usd per share) \| $ / shares	48.45
Weighted-average grant date fair value of nonvested restricted RSUs, forfeited or cancelled (in usd per share) \| $ / shares	63.36
Weighted-average grant date fair value, ending balance (in usd per share) \| $ / shares	$ 82.33

Stock Based Compensation - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 4,390	$ 2,499
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	72	175
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	768	453
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	614	395
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,936	$ 1,476

Commitments and Contingencies - Additional Information (Details) $ in Thousands		3 Months Ended
	Jun. 15, 2020 USD ($) a	Mar. 31, 2021 USD ($)	Aug. 01, 2020 USD ($)	May 16, 2020 a
Lessee, Lease, Description [Line Items]
Annual minimum commitment, year one			$ 600
Annual minimum commitment, year two			$ 300
Non-cancellable purchase obligation		$ 14,386
Non-cancellable purchase obligation, fulfilled within a year		8,519
Land (acres) \| a	40			40
Maximum reimbursement of predevelopment work expenses		$ 597
Proposed
Lessee, Lease, Description [Line Items]
Consideration for the proposed Land purchase	$ 30,000
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term		5 years 9 months

Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Matching contributions	$ 912	$ 634
Non-U.S. \| Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost	$ 104	$ 0

Employee Benefit Plans - Summary of Net Periodic Cost of Pension and Postretirement Benefit Plans (Details) - Pension Plan - Non-U.S. - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 103
Interest cost	5
Return on plan assets	(4)
Net periodic pension cost	104	$ 0
Total recognized in net periodic benefit cost	$ 104
Expected long-term rate of return on plan assets	0.50%

Income Taxes - Additional Information (Details)	3 Months Ended
Income Taxes - Additional Information (Details)	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Effective tax rate	5.90%	72.10%

Related Parties (Details) - Affiliated Entity - Republic - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Amount collected on behalf	$ 344,000	$ 308,000
Facilities Sharing Agreement
Related Party Transaction [Line Items]
Reduction of rent expense	96,000	96,000
Due from related parties	0		$ 0
Tax Sharing Agreement
Related Party Transaction [Line Items]
Due from related parties	0		0
Master Services Agreement
Related Party Transaction [Line Items]
Revenue from related parties	487,000	533,000
Accounts receivable, related parties	153,000		170,000
Services Agreement
Related Party Transaction [Line Items]
Revenue from related parties	6,000	$ 31,000
Accounts receivable, related parties	$ 2,000		$ 2,000

Basic and Diluted Loss per Common Share - Components of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Earnings Per Share [Abstract]
Net income (loss)	$ (5,316)	$ (19,926)	$ (2,352)	$ (20,641)	$ (1,058)
Less: net income allocated to participating securities	0				0
Net loss attributable to common stockholders	$ (5,316)				$ (1,058)
Net loss per share:
Basic (in usd per share)	$ (0.21)				$ (0.04)
Diluted (in usd per share)	$ (0.21)				$ (0.04)
Weighted Average Number of Common Shares Outstanding
Basic (in shares)	25,015,948				23,563,569
Diluted (in shares)	25,015,948				23,563,569

Basic and Diluted Loss per Common Share - Schedule of Antidilutive Common Share Equivalents Excluded from Earnings Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	2,414,442	1,314,975
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	196,433	820,966
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	405,875	494,009
Convertible Debt Securities
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,812,134