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.