Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	On July 8, 2022, Acorn MergeCo, Inc. (“Merger Sub”), a Delaware corporation and wholly-owned direct subsidiary of ADTRAN Holdings, Inc. (formerly known as Acorn HoldCo), merged with and into ADTRAN, Inc., with ADTRAN, Inc. surviving the merger as a wholly-owned direct subsidiary of ADTRAN Holdings, Inc. (the “Merger”). The Merger was consummated pursuant to the Business Combination Agreement, dated as of August 30, 2021 (the “Business Combination Agreement”), by and among ADTRAN Holdings, Inc., ADTRAN, Inc., ADVA Optical Networking SE, a company organized and existing under the laws of Germany (“ADVA”), and Merger Sub. In accordance with the Business Combination Agreement, ADTRAN Holdings, Inc. made a public offer to exchange each issued and outstanding no-par value bearer share of ADVA for 0.8244 shares of common stock, par value $0.01 per share (the “Company Common Stock”), of ADTRAN Holdings, Inc. (the “Exchange Offer” and, together with the Merger, the “Business Combination”). On July 15, 2022 (the “Exchange Offer Settlement Date”), ADTRAN Holdings, Inc. completed the Exchange Offer, in which ADTRAN Holdings, Inc. acquired 33,957,538 bearer shares of ADVA, or 65.43% of ADVA’s outstanding bearer shares as of the Exchange Offer Settlement Date, in exchange for the issuance of an aggregate of 27,994,595 shares of common stock of ADTRAN Holdings, Inc. Except as otherwise indicated, references in these notes to “ADTRAN,” the “Company,” “we,” “us” and “our” for time periods at and before the effectiveness of the Merger, including all fiscal periods ended on or prior to June 30, 2022, shall be deemed to refer to ADTRAN, Inc. as the predecessor registrant to ADTRAN Holdings, Inc. 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying unaudited condensed consolidated financial statements of ADTRAN and its subsidiaries have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) applicable to interim financial information presented in Quarterly Reports on Form 10-Q. Accordingly, certain information and notes required by generally accepted accounting principles in the United States of America (“U.S. GAAP”) for complete financial statements are not included herein. Certain prior year amounts have been reclassified to conform to the current period presentation. The December 31, 2021 Condensed Consolidated Balance Sheet is derived from audited financial statements but does not include all disclosures required by U.S. GAAP. In the opinion of management, all adjustments necessary to fairly state these interim statements have been recorded and are of a normal and recurring nature. The results of operations for an interim period are not necessarily indicative of the results for the full year. The interim financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in ADTRAN, Inc. Annual Report on Form 10-K for the year ended December 31, 2021, filed with the SEC on February 25, 2022. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. Significant estimates include excess and obsolete inventory reserves, warranty reserves, customer rebates, determination and accrual of the deferred revenue related to performance obligations under contracts with customers, estimated costs to complete obligations associated with deferred and accrued revenues and network installations, estimated income tax provision and income tax contingencies, fair value of stock-based compensation, assessment of goodwill and other intangibles for impairment, estimated lives of intangible assets, estimated pension liability and fair value of investments. Actual amounts could differ significantly from these estimates. We assessed certain accounting matters that generally require consideration of forecasted financial information in context with the information reasonably available to us and the unknown future impacts of the SARS-CoV-2 coronavirus/COVID-19 global pandemic (or variants of the SARS-CoV-2 coronavirus) as well as supply chain constraints as of June 30, 2022 and through the date of this report. The accounting matters assessed included, but were not limited to, the allowance for credit losses, stock-based compensation, carrying value of goodwill, intangibles and other long-lived assets, financial assets, valuation allowances for tax assets, revenue recognition and costs of revenue. Future conditions related to the magnitude and duration of the COVID-19 pandemic, as well as other factors, including supply chain constraints, could result in further impacts to our consolidated financial statements in future reporting periods. Recently Adopted Accounting Pronouncements There are currently no recently adopted accounting pronouncements that had a material effect on the condensed consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted In October 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update ("ASU") 2021-08, Business Combinations (Topic 805) Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which would require an acquirer to recognize and measure acquired contract assets and contract liabilities in a manner consistent with how the acquiree recognized and measured them in its pre-acquisition financial statements in accordance with Topic 606, Revenue Recognition. ASU 2021-08 is effective for annual periods beginning after December 15, 2022, including interim periods within those fiscal years. Adoption of the ASU should be applied prospectively. Early adoption is also permitted, including adoption in an interim period. If early adopted, the amendments are applied retrospectively to all business combinations for which the acquisition date occurred during the fiscal year of adoption. Given that the Business Combination with ADVA was finalized in July 2022, the Company plans to early adopt ASU 2021-08 during the third quarter of 2022. ASU 2021-08 will be effective as of January 1, 2022 and will be applied on a prospective basis. However, we are unable to estimate the effect on our Condensed Consolidated Financial Statements as of the date of this report.

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2022

Summary of Significant Accounting Policies

On July 8, 2022, Acorn MergeCo, Inc. (“Merger Sub”), a Delaware corporation and wholly-owned direct subsidiary of ADTRAN Holdings, Inc. (formerly known as Acorn HoldCo), merged with and into ADTRAN, Inc., with ADTRAN, Inc. surviving the merger as a wholly-owned direct subsidiary of ADTRAN Holdings, Inc. (the “Merger”). The Merger was consummated pursuant to the Business Combination Agreement, dated as of August 30, 2021 (the “Business Combination Agreement”), by and among ADTRAN Holdings, Inc., ADTRAN, Inc., ADVA Optical Networking SE, a company organized and existing under the laws of Germany (“ADVA”), and Merger Sub. In accordance with the Business Combination Agreement, ADTRAN Holdings, Inc. made a public offer to exchange each issued and outstanding no-par value bearer share of ADVA for 0.8244 shares of common stock, par value $0.01 per share (the “Company Common Stock”), of ADTRAN Holdings, Inc. (the “Exchange Offer” and, together with the Merger, the “Business Combination”). On July 15, 2022 (the “Exchange Offer Settlement Date”), ADTRAN Holdings, Inc. completed the Exchange Offer, in which ADTRAN Holdings, Inc. acquired 33,957,538 bearer shares of ADVA, or 65.43% of ADVA’s outstanding bearer shares as of the Exchange Offer Settlement Date, in exchange for the issuance of an aggregate of 27,994,595 shares of common stock of ADTRAN Holdings, Inc.

Except as otherwise indicated, references in these notes to “ADTRAN,” the “Company,” “we,” “us” and “our” for time periods at and before the effectiveness of the Merger, including all fiscal periods ended on or prior to June 30, 2022, shall be deemed to refer to ADTRAN, Inc. as the predecessor registrant to ADTRAN Holdings, Inc.

1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of ADTRAN and its subsidiaries have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) applicable to interim financial information presented in Quarterly Reports on Form 10-Q. Accordingly, certain information and notes required by generally accepted accounting principles in the United States of America (“U.S. GAAP”) for complete financial statements are not included herein. Certain prior year amounts have been reclassified to conform to the current period presentation. The December 31, 2021 Condensed Consolidated Balance Sheet is derived from audited financial statements but does not include all disclosures required by U.S. GAAP.

In the opinion of management, all adjustments necessary to fairly state these interim statements have been recorded and are of a normal and recurring nature. The results of operations for an interim period are not necessarily indicative of the results for the full year. The interim financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in ADTRAN, Inc. Annual Report on Form 10-K for the year ended December 31, 2021, filed with the SEC on February 25, 2022.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the reporting period. Significant estimates include excess and obsolete inventory reserves, warranty reserves, customer rebates, determination and accrual of the deferred revenue related to performance obligations under contracts with customers, estimated costs to complete obligations associated with deferred and accrued revenues and network installations, estimated income tax provision and income tax contingencies, fair value of stock-based compensation, assessment of goodwill and other intangibles for impairment, estimated lives of intangible assets, estimated pension liability and fair value of investments. Actual amounts could differ significantly from these estimates.

We assessed certain accounting matters that generally require consideration of forecasted financial information in context with the information reasonably available to us and the unknown future impacts of the SARS-CoV-2 coronavirus/COVID-19 global pandemic (or variants of the SARS-CoV-2 coronavirus) as well as supply chain constraints as of June 30, 2022 and through the date of this report. The accounting matters assessed included, but were not limited to, the allowance for credit losses, stock-based compensation, carrying value of goodwill, intangibles and other long-lived assets, financial assets, valuation allowances for tax assets, revenue recognition and costs of revenue. Future conditions related to the magnitude and duration of the COVID-19 pandemic, as well as other factors, including supply chain constraints, could result in further impacts to our consolidated financial statements in future reporting periods.

Recently Adopted Accounting Pronouncements

There are currently no recently adopted accounting pronouncements that had a material effect on the condensed consolidated financial statements.

Recent Accounting Pronouncements Not Yet Adopted

In October 2021, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update ("ASU") 2021-08, Business Combinations (Topic 805) Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, which would require an acquirer to recognize and measure acquired contract assets and contract liabilities in a manner consistent with how the acquiree recognized and measured them in its pre-acquisition financial statements in accordance with Topic 606, Revenue Recognition. ASU 2021-08 is effective for annual periods beginning after December 15, 2022, including interim periods within those fiscal years. Adoption of the ASU should be applied prospectively. Early adoption is also permitted, including adoption in an interim period. If early adopted, the amendments are applied retrospectively to all business combinations for which the acquisition date occurred during the fiscal year of adoption. Given that the Business Combination with ADVA was finalized in July 2022, the Company plans to early adopt ASU 2021-08 during the third quarter of 2022. ASU 2021-08 will be effective as of January 1, 2022 and will be applied on a prospective basis. However, we are unable to estimate the effect on our Condensed Consolidated Financial Statements as of the date of this report.