ADTRAN (ADTN) 10-Q 9 Nov 22 2022 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2022	Nov. 07, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Entity Registrant Name	ADTRAN Holdings, Inc.
Trading Symbol	ADTN
Entity Central Index Key	0000926282
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		77,655,939
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	001-41446
Entity Tax Identification Number	87-2164282
Entity Address, Address Line One	901 Explorer Boulevard
Entity Address, City or Town	Huntsville
Entity Address, State or Province	AL
Entity Address, Postal Zip Code	35806-2807
City Area Code	256
Local Phone Number	963-8000
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, Par Value $0.01 per share
Security Exchange Name	NASDAQ

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current Assets
Cash and cash equivalents	$ 111,099	$ 56,603
Restricted cash		215
Short-term investments (includes $803 and $350 of available-for-sale securities as of September 30, 2022 and December 31, 2021, respectively, reported at fair value)	803	350
Accounts receivable, less allowance for credit looses of $281 and $0 as of September 30, 2022 and December 31, 2021, respectively	302,401	158,742
Other receivables	14,350	11,228
Inventory, net	416,163	139,891
Prepaid expenses and other current assets	30,739	9,296
Total Current Assets	875,555	376,325
Property, plant and equipment, net	104,577	55,766
Deferred tax assets, net		9,079
Goodwill	357,869	6,968
Intangibles, net	393,575	19,293
Other non-current assets	56,347	30,971
Long-term investments (includes $27,860 and $29,717 of available-for-sale securities as of September 30, 2022 and December 31, 2021, respectively, reported at fair value)	50,131	70,615
Total Assets	1,838,054	569,017
Current Liabilities
Accounts payable	276,026	102,489
Revolving credit agreements outstanding	84,503
Notes Payable	29,782
Unearned revenue	40,993	17,737
Accrued expenses and other liabilities	25,554	13,673
Accrued wages and benefits	41,595	14,900
Income tax payable, net	26,838	6,560
Total Current Liabilities	525,291	155,359
Deferred tax liabilities, net	36,884
Non-current unearned revenue	18,269	9,271
Pension liability	16,220	11,402
Deferred compensation liability	25,376	31,383
Non-current lease obligations	21,490	3,269
Other non-current liabilities	9,697	1,231
Total Liabilities	653,227	211,915
Commitments and contingencies (see Note 20)
Equity
Common stock, par value $0.01 per share; 200,000 shares authorized; 77,619 shares issued and outstanding as of September 30, 2022 and 79,652 shares issued and 49,063 shares outstanding as of December 31, 2021	776	797
Additional paid-in capital	883,210	288,946
Accumulated other comprehensive loss	(40,288)	(11,914)
Retained earnings	31,535	740,820
Treasury stock at cost: 197 and 30,590 shares as of September 30, 2022 and December 31, 2021, respectively	(4,083)	(661,547)
Non-controlling interest	313,677
Total Equity	1,184,827	357,102
Total Liabilities and Equity	$ 1,838,054	$ 569,017

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Short-term investments, available-for-sale securities at fair value	$ 803	$ 350
Accounts receivable, allowance for credit losses	218	0
Long-term investments, available-for-sale securities fair value	$ 27,860	$ 29,717
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	77,619,000	79,652,000
Common stock, shares outstanding	77,619,000	49,063,000
Treasury stock, shares	197,000	30,590,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenue
Total Revenue	$ 340,709	$ 138,081	$ 667,265	$ 408,846
Cost of Revenue
Total Cost of Revenue	237,682	90,408	447,416	244,904
Gross Profit	103,027	47,673	219,849	163,942
Selling, general and administrative expenses	74,880	30,972	130,646	89,273
Research and development expenses	59,196	26,759	112,187	82,131
Asset impairments	16,969		16,969
Operating Loss	(48,018)	(10,058)	(39,953)	(7,462)
Interest and dividend income	347	344	768	887
Interest expense	(1,303)	(6)	(1,427)	(18)
Net investment (loss) gain	(2,691)	(63)	(10,752)	2,942
Other income, net	2,494	648	2,949	2,673
Loss Before Income Taxes	(49,171)	(9,135)	(48,415)	(978)
Income tax benefit (expense)	4,312	(1,292)	4,572	(3,467)
Net Loss	(44,859)	(10,427)	(43,843)	(4,445)
Less: Net Loss attributable to non-controlling interest	(2,925)		(2,925)
Net Loss attributable to ADTRAN Holdings, Inc.	$ (41,934)	$ (10,427)	$ (40,918)	$ (4,445)
Weighted average shares outstanding – basic	73,036	48,609	57,175	48,470
Weighted average shares outstanding – diluted	73,036	48,609	57,175	48,470
Loss per common share attributable to ADTRAN Holdings, Inc. - basic	$ (0.57)	$ (0.21)	$ (0.72)	$ (0.09)
Loss per common share attributable to ADTRAN Holdings, Inc. - diluted	$ (0.57)	$ (0.21)	$ (0.72)	$ (0.09)
Network Solutions [Member]
Revenue
Total Revenue	$ 304,940	$ 120,767	$ 599,306	$ 360,025
Cost of Revenue
Total Cost of Revenue	222,606	81,029	413,180	216,044
Gross Profit	82,334	39,738	186,126	143,981
Services & Support [Member]
Revenue
Total Revenue	35,769	17,314	67,959	48,821
Cost of Revenue
Total Cost of Revenue	15,076	9,379	34,236	28,860
Gross Profit	$ 20,693	$ 7,935	$ 33,723	$ 19,961

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net Loss	$ (44,859)	$ (10,427)	$ (43,843)	$ (4,445)
Other Comprehensive Loss, net of tax
Net unrealized loss on available-for-sale securities	(396)	(61)	(1,320)	(348)
Defined benefit plan adjustments	118	124	(218)	435
Foreign currency translation loss	(23,172)	(1,389)	(26,930)	(2,914)
Other Comprehensive Loss, net of tax	(23,686)	(1,326)	(28,468)	(2,827)
Less: Comprehensive Loss attributable to non-controlling interest, net of tax	(94)		(94)
Comprehensive Loss attributable to ADTRAN Holdings, Inc., net of tax	$ (68,451)	$ (11,753)	$ (72,217)	$ (7,272)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	ADVA Optical Networking SE, [Member]	Common Stock [Member]	Common Stock [Member] ADVA Optical Networking SE, [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] ADVA Optical Networking SE, [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Non-controlling Interest [Member]	Non-controlling Interest [Member] ADVA Optical Networking SE, [Member]
Beginning Balance at Dec. 31, 2020	$ 372,944		$ 797		$ 281,466		$ 781,813	$ (679,493)	$ (11,639)
Beginning Balance, Shares at Dec. 31, 2020			79,652
Net income (loss)	896						896
Other comprehensive income (loss), net of tax	(1,956)								(1,956)
Dividend payments ($0.09 per share)	(4,361)						(4,361)
Dividends accrued on unvested RSUs	(68)						(68)
Deferred compensation adjustments, net of tax	(50)							(50)
PSUs, RSUs and restricted stock vested	(81)						(1,683)	1,602
Stock options exercised	1,244						(476)	1,720
Stock-based compensation expense	1,807				1,807
Ending Balance at Mar. 31, 2021	370,375		$ 797		283,273		776,121	(676,221)	(13,595)
Ending Balance, Shares at Mar. 31, 2021			79,652
Beginning Balance at Dec. 31, 2020	372,944		$ 797		281,466		781,813	(679,493)	(11,639)
Beginning Balance, Shares at Dec. 31, 2020			79,652
Net income (loss)	(4,445)
Other comprehensive income (loss), net of tax	(2,827)
Ending Balance at Sep. 30, 2021	363,753		$ 797		286,923		760,398	(669,899)	(14,466)
Ending Balance, Shares at Sep. 30, 2021			79,652
Beginning Balance at Mar. 31, 2021	370,375		$ 797		283,273		776,121	(676,221)	(13,595)
Beginning Balance, Shares at Mar. 31, 2021			79,652
Net income (loss)	5,086						5,086
Other comprehensive income (loss), net of tax	455								455
Dividend payments ($0.09 per share)	(4,374)						(4,374)
Dividends accrued on unvested RSUs	(128)						(128)
Deferred compensation adjustments, net of tax	(12)							(12)
PSUs, RSUs and restricted stock vested	(3)						(32)	29
Stock options exercised	2,308						(619)	2,927
Stock-based compensation expense	1,808				1,808
Ending Balance at Jun. 30, 2021	375,515		$ 797		285,081		776,054	(673,277)	(13,140)
Ending Balance, Shares at Jun. 30, 2021			79,652
Net income (loss)	(10,427)						(10,427)
Other comprehensive income (loss), net of tax	(1,326)								(1,326)
Dividend payments ($0.09 per share)	(4,389)						(4,389)
Dividends accrued on unvested RSUs	2						2
Deferred compensation adjustments, net of tax	(12)							(12)
PSUs, RSUs and restricted stock vested	(11)						(185)	174
Stock options exercised	2,559						(657)	3,216
Stock-based compensation expense	1,842				1,842
Ending Balance at Sep. 30, 2021	363,753		$ 797		286,923		760,398	(669,899)	(14,466)
Ending Balance, Shares at Sep. 30, 2021			79,652
Beginning Balance at Dec. 31, 2021	$ 357,102		$ 797		288,946		740,820	(661,547)	(11,914)
Beginning Balance, Shares at Dec. 31, 2021	79,652		79,652
Net income (loss)	$ (1,127)						(1,127)
Other comprehensive income (loss), net of tax	(1,642)								(1,642)
Dividend payments ($0.09 per share)	(4,438)						(4,438)
Dividends accrued on unvested RSUs	32						32
Deferred compensation adjustments, net of tax	(18)							(18)
PSUs, RSUs and restricted stock vested	(54)						(895)	841
Stock options exercised	568						(143)	711
Stock-based compensation expense	1,893				1,893
Ending Balance at Mar. 31, 2022	352,316		$ 797		290,839		734,249	(660,013)	(13,556)
Ending Balance, Shares at Mar. 31, 2022			79,652
Beginning Balance at Dec. 31, 2021	$ 357,102		$ 797		288,946		740,820	(661,547)	(11,914)
Beginning Balance, Shares at Dec. 31, 2021	79,652		79,652
Net income (loss)	$ (43,843)
Other comprehensive income (loss), net of tax	$ (28,468)
Stock options exercised, Shares	439
Ending Balance at Sep. 30, 2022	$ 1,184,827		$ 776		883,210		31,535	(4,083)	(40,288)	$ 313,677
Ending Balance, Shares at Sep. 30, 2022	77,619		77,619
Beginning Balance at Mar. 31, 2022	$ 352,316		$ 797		290,839		734,249	(660,013)	(13,556)
Beginning Balance, Shares at Mar. 31, 2022			79,652
Net income (loss)	2,143						2,143
Other comprehensive income (loss), net of tax	(3,140)								(3,140)
Dividend payments ($0.09 per share)	(4,439)						(4,439)
Dividends accrued on unvested RSUs	(23)						(23)
Deferred compensation adjustments, net of tax	24							24
PSUs, RSUs and restricted stock vested	(300)						(90)	(210)
Stock options exercised	68						(19)	87
Stock-based compensation expense	1,888				1,888
Ending Balance at Jun. 30, 2022	348,537		$ 797		292,727		731,821	(660,112)	(16,696)
Ending Balance, Shares at Jun. 30, 2022			79,652
Net income (loss)	(44,859)						(41,934)			(2,925)
Acquisition of ADVA		$ 894,675		$ 280		$ 577,980					$ 316,415
Acquisition of ADVA, Shares				27,995
Retirement of treasury stock			$ (303)				(655,761)	656,064
Retirement of treasury stock, Shares			(30,330)
Other comprehensive income (loss), net of tax	(23,686)								(23,592)	(94)
Dividend payments ($0.09 per share)	(6,982)						(6,982)
Deferred compensation adjustments, net of tax	(35)							(35)
PSUs, RSUs and restricted stock vested	(40)						(40)
PSUs, RSUs and restricted stock vested, Shares			4
Stock options exercised	4,433	365	$ 2			236	4,431				129
Stock options exercised, Shares			298
Stock-based compensation expense	11,195	$ 938			11,195	$ 885					$ 53
Reclassification of ADVA stock options	286				187					99
Ending Balance at Sep. 30, 2022	$ 1,184,827		$ 776		$ 883,210		$ 31,535	$ (4,083)	$ (40,288)	$ 313,677
Ending Balance, Shares at Sep. 30, 2022	77,619		77,619

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021
Statement of Stockholders' Equity [Abstract]
Dividend payments	$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.09

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities:
Net Loss	$ (43,843)	$ (4,445)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	34,783	12,246
Asset impairments	16,969
Amortization of debt issuance cost	200
Loss (gain) on investments, net	10,395	(3,320)
Stock-based compensation expense	15,912	5,457
Deferred income taxes	(26,366)	437
Other, net	32	89
Inventory reserves	(6,681)	(4,789)
Changes in operating assets and liabilities:
Accounts receivable, net	(34,535)	(26,346)
Other receivables	(2,154)	11,152
Inventory	(76,293)	2,120
Prepaid expenses, other current assets and other assets	610	(8,514)
Accounts payable	70,381	29,614
Accrued expenses and other liabilities	(23,005)	10,392
Income taxes payable, net	20,862	4,798
Net cash (used in) provided by operating activities	(42,733)	28,891
Cash flows from investing activities:
Purchases of property, plant and equipment	(10,141)	(3,572)
Proceeds from sales and maturities of available-for-sale investments	30,474	28,305
Purchases of available-for-sale investments	(22,215)	(28,853)
Proceeds from beneficial interests in securitized accounts receivable	1,294
Proceeds from disposals of property, plant and equipment	12
Insurance proceeds received		500
Acquisition of business, net of cash acquired	43,957
Net cash provided by (used in) investing activities	43,381	(3,620)
Cash flows from financing activities:
Tax withholdings related to stock-based compensation settlements	(515)	(113)
Proceeds from stock option exercises	5,434	6,111
Dividend payments	(15,859)	(13,124)
Proceeds from draw on revolving credit agreements	133,141
Repayment of revolving credit agreements	(48,000)
Payment of debt issuance cost	3,015
Repayment of notes payable	(10,057)
Net cash provided by (used in) financing activities	61,129	(7,126)
Net increase in cash, cash equivalents and restricted cash	61,777	18,145
Effect of exchange rate changes	(7,496)	(2,719)
Cash, cash equivalents and restricted cash, beginning of period	56,818	60,179
Cash, cash equivalents and restricted cash, end of period	111,099	75,605
Supplemental disclosure of cash financing activities:
Cash paid for interest	633
Supplemental disclosure of non-cash investing activities:
Right-of-use assets obtained in exchange for lease obligations	904	1,833
Purchases of property, plant and equipment included in accounts payable	1,037	$ 100
ADVA common shares exchanged in acquisition	565,491
ADVA options issued in acquisition	12,769
Noncontrolling interest related to ADVA	$ 316,415

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	GENERAL On July 8, 2022, Acorn MergeCo, Inc. (“Merger Sub”), a Delaware corporation and wholly-owned direct subsidiary of ADTRAN Holdings, Inc. (f/k/a Acorn HoldCo, Inc.), 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 34.0 million 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 28.0 million shares of Company Common Stock. See Note 2 for additional information. On October 18, 2022, the Board of Directors of the Company and the management board of ADVA agreed on a final draft of a domination and profit and loss transfer agreement (the “DPLTA”) between the Company, as the controlling company, and ADVA, as the controlled company. The parties’ execution of the DPLTA remains subject to approval of the DPLTA by shareholders of ADVA with 75 % of the votes cast in an extraordinary general meeting, which is scheduled to be held on November 30, 2022. If and when signed, effectiveness of the DPLTA is subject to the subsequent registration of the DPLTA with the commercial register (Handelsregister) of the local court (Amtsgericht) at the registered offices of ADVA, with such effectiveness to occur no earlier than January 1, 2023. The Company currently holds 33,957,538 shares of ADVA, representing 65.35 % of ADVA’s outstanding shares on September 30, 2022. Unless the context otherwise indicates or requires, references in this Quarterly Report on Form 10-Q to “ADTRAN,” the “Company,” “we,” “us” and “our” refer to ADTRAN, Inc. and its consolidated subsidiaries prior to the Merger on July 8, 2022, and to ADTRAN Holdings, Inc. and its consolidated subsidiaries following the Merger. 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements of ADTRAN Holdings, Inc. and its subsidiaries have been prepared pursuant to the rules and regulations of 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 allowance for credit losses on accounts receivable and contract assets, 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), supply chain constraints, inflationary pressures, the energy crisis, currency fluctuations and political tensions as of September 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 and inflationary pressures could result in further impacts to the Company's consolidated financial statements in future reporting periods. Recently Adopted Accounting Pronouncements 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. The Company early adopted ASU 2021-08 on July 1, 2022 and the standard was applied retrospectively beginning with January 1, 2022. The effect of the adoption of this standard on the Company's Condensed Consolidated Financial Statements as of the date of this report is included in Note 2 of the Notes to Condensed Consolidated Financial Statements . Recent Accounting Pronouncements Not Yet Adopted There are currently no accounting pronouncements not yet adopted that had a material effect on the Condensed Consolidated Financial Statements.

Business Combination

Business Combination	9 Months Ended
	Sep. 30, 2022
Business Combinations [Abstract]
Business Combination	2. BUSINESS COMBINATION ADVA Optical Networking SE On August 30, 2021 , ADTRAN and ADVA, entered into a Business Combination Agreement, pursuant to which both companies agreed to combine their respective businesses and each become subsidiaries of a new holding company, ADTRAN Holdings, Inc. (formerly known as Acorn HoldCo, Inc.) which was formed as a wholly-owned subsidiary of ADTRAN in order to consummate the transactions under the Business Combination Agreement. Under the terms of the Business Combination Agreement, on July 8, 2022, Acorn MergeCo, Inc, a Delaware corporation and wholly-owned direct subsidiary of the Company, merged with and into ADTRAN Holdings, Inc. with ADTRAN Holdings, Inc. surviving the Business Combination as a wholly-owned direct subsidiary of the Company. Additionally, pursuant to the Business Combination Agreement, the Company made a public offer to exchange each issued and outstanding no-par value bearer share of ADVA for 0.8244 shares of Company Common Stock, par value $ 0.01 per share of the Company. The Exchange Offer was settled on Exchange Offer Settlement Date, on which date the Company 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 Company Common Stock. Additionally, pursuant to the Business Combination Agreement, ADVA stock option holders were entitled to have their ADVA stock options assumed by ADTRAN Holdings, Inc. (applying the exchange ratio in the Business Combination Agreement), thereafter representing options to acquire stock of ADTRAN, Inc. The fair value of the ADVA stock options assumed by ADTRAN, Inc. was $ 12.8 million, estimated using the Monte Carlo method. ADTRAN, Inc. and ADVA became subsidiaries of ADTRAN Holdings, Inc. as a result of the Business Combination. ADTRAN was determined to be the accounting acquirer of ADVA based on ADTRAN shareholders’ majority equity stake in the combined company, the composition of the board of directors and senior management of the combined company, among other factors. The Business Combination of ADVA has been accounted for using the acquisition method of accounting as per the provisions of Accounting Standards Codification 805, “Business Combinations” (“ASC 805”). The Business Combination Agreement used a fixed exchange ratio of Company Common Stock for ADVA shares of common stock, which resulted in a 36 % equity stake for ADVA stockholders and 64 % equity stake for ADTRAN stockholders in the post-closing combined company (calculated on a fully diluted basis and utilizing the tender of 65.43 % of ADVA’s current issued and outstanding share capital). Therefore, ADTRAN shareholders continue to hold a majority interest in the combined company after the Business Combination was completed. Additionally, the Board of Directors is comprised of six members from ADTRAN and three members from ADVA; the current ADTRAN chief executive officer acts as the chairman of the Board of Directors and the former ADVA chief executive officer as the vice chairman of the Board of Directors. Additionally, the current ADTRAN chief executive officer and ADTRAN chief financial officer hold these positions within the combined company. After these and other considerations as outlined in ASC 805, ADTRAN represents the accounting acquirer. The following table summarizes the purchase price for the ADVA business combination: (In thousands, except shares, share price and exchange ratio) Purchase Price ADVA shares exchanged 33,957,538 Exchange ratio 0.8244 ADTRAN Holdings, Inc. shares issued 27,994,595 ADTRAN Holdings, Inc. share price on July 15, 2022 $ 20.20 Purchase price paid for ADVA shares $ 565,491 Equity compensation (1) $ 12,769 Total purchase price $ 578,260 (1) Represents the portion of replacement share-based payment awards that relates to pre-combination vesting. Assets acquired and liabilities assumed were recognized at their respective fair values as of July 15, 2022. The following table summarizes the preliminary purchase price allocation for each major class of assets acquired and liabilities assumed in the acquisition of ADVA (in thousands): (In thousands) Total purchase price $ 578,260 Non-controlling interest $ 316,415 Net Assets: Cash and cash equivalents $ 44,003 Accounts receivable 114,659 Other receivables 1,457 Inventory 200,532 Prepaid expenses and other current assets 29,474 Property plant and equipment 52,796 Deferred tax assets 1,599 Intangibles 405,385 Other non-current assets 30,588 Accounts payable ( 98,587 ) Current unearned revenue ( 26,047 ) Accrued expenses and other liabilities ( 59,600 ) Current portion of notes payable ( 25,254 ) Income tax payable ( 1,400 ) Non-current unearned revenue ( 11,498 ) Pension liability ( 6,820 ) Other non-current liabilities ( 6,094 ) Non-current portion of revolving credit agreements and notes payable ( 15,250 ) Non-current lease obligations ( 20,046 ) Deferred tax liabilities ( 74,379 ) Total net assets acquired $ 535,518 Goodwill $ 359,157 The allocation of the purchase price and fair value assessment of goodwill, property, plant and equipment, intangible assets, inventory, deferred tax assets, and deferred tax liabilities is preliminary as a result of ongoing valuation procedures on the assets acquired and liabilities assumed. The acquisition accounting is subject to revision once the Company receives final information. It is possible that the final assessment of fair value may differ materially from the preliminary assessment. If the final assessment differs from this preliminary assessment, the measurement period adjustments will be recorded in the period in which they are determined as if they had been completed at the acquisition date. The preliminary fair value of the assets acquired include accounts receivable of $ 114.7 million and other receivables of $ 1.5 million. The unpaid principal balance under these receivables is $ 118.5 million and $ 1.5 million, respectively. The difference between the fair value and the unpaid principal balance primarily represents amounts expected to be uncollectible. The fair value of the intangible assets acquired as of the acquisition date: (In thousands) Estimated-average useful life (in years) (1) Fair value Income Statement Amortization Classification Developed technology 8.5 $ 293,530 Cost of revenue - Network Solutions Backlog 1.4 52,165 Cost of revenue - Network Solutions and Services & Support Customer relationships 10.5 32,704 Selling, general and administrative expenses Trade name 2.8 26,986 Selling, general and administrative expenses Total $ 405,385 (1) Determination of the weighted average period of the individual categories of intangible assets was based on the nature of the applicable intangible asset and the expected future cash flows to be derived from the intangible asset. Amortization of intangible assets with definite lives is recognized over the period of time the assets are expected to contribute to future cash flows. Goodwill represents the excess of the purchase price over the fair value of the net tangible and intangible assets acquired. Based on preliminary estimates, the ADVA acquisition resulted in the recognition of goodwill of $ 359.2 million, which the Company believes is attributable to the value driven by the Company’s expected growth of the business, synergies, and expanded market and product opportunities. Goodwill created as a result of the ADVA acquisition is not deductible for tax purposes. After the Business Combination, the chief operating decision maker assessed and will continue to assess the Company’s performance and allocate resources to its two segments (1) Network Solutions and (2) Services & Support. Based on preliminary estimates, the goodwill resulting from the Business Combination of $ 270.6 million was allocated to the Network Solutions segment, and $ 88.6 million was allocated to the Services & Support segment. See Note 18 of the Notes to Condensed Consolidated Financial Statements, included in Part I, Item 1 of this report for more information about the Company’s segments. As of the acquisition date, the fair value of the non-controlling interest was approximately $ 316.4 million and determined using a market approach. As a portion of ADVA shares will remain trading after the Business Combination, the non-controlling interest was calculated using 17,941,496 ADVA shares held by non-controlling interest multiplied by the ADVA closing share price of € 17.58 ($ 17.64 using the July 15, 2022 EUR to USD conversion rate of $ 1.00318 ) on July 15, 2022. The Company included the financial results of ADVA in its consolidated financial statements since July 15, 2022, the acquisition date. The net revenue and net loss from the ADVA business since July 15, 2022, were $ 163.8 million and $ 8.4 million, respectively, which are included in the Company’s Condensed Consolidated Statement of Loss. The net loss attributable to non-controlling interest from the ADVA business for the three and nine months ended September 30, 2022 was $ 2.9 million. As of September 30, 2022, the Company has incurred $ 25.2 million of transaction costs related to the Business Combination, of which $ 10.6 million and $ 5.1 million were incurred during the three months ended September 30, 2022 and 2021, respectively and $ 13.3 million and $ 6.4 million were incurred during the nine months ended September, 30 2022 and 2021, respectively. The Company expects to incur an estimated $ 1.1 million of additional transaction costs related to the Business Combination. These transaction costs are recorded in selling, general and administrative expense in the Condensed Consolidated Statements of Loss. Supplemental Pro Forma Information (Unaudited) The unaudited pro forma financial information in the table below summarizes the combined results of operations for ADTRAN and ADVA as though the Business Combination had occurred on January 1, 2021. The pro forma amounts have been adjusted for differences in basis of accounting which are determined before taking into effect the impacts of purchase accounting and Business Combination accounting impacts. The following unaudited pro forma information is presented for illustrative purposes only. It is not necessarily indicative of the results of operations of future periods, the results of operations that actually would have been realized had the entities been a single company as of January 1, 2021, or the future operating results of the combined entities. The unaudited pro forma information does not give effect to the potential impact of current financial conditions, regulatory matters or any anticipated synergies, operating efficiencies or cost savings that may be associated with the acquisition. The unaudited pro forma information also does not include any integration costs or remaining future transaction costs that the Company may incur related to the acquisition as part of combining the operations of the companies. Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Revenue $ 368,192 $ 317,067 $ 1,053,510 $ 942,003 Net income (loss) $ ( 48,084 ) $ ( 44,154 ) $ ( 60,494 ) $ ( 133,321 )

Cash, Cash Equivalents and Rest

Cash, Cash Equivalents and Restricted Cash	9 Months Ended
	Sep. 30, 2022
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Restricted Cash	3. CASH, CASH EQUIVALENTS AND RESTRICTED CASH The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statements of Cash Flows: As of As of (In thousands) September 30, 2022 December 31, 2021 Cash and cash equivalents $ 111,099 $ 56,603 Restricted cash — 215 Cash, cash equivalents and restricted cash $ 111,099 $ 56,818

Revenue

Revenue	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Revenue	4. REVENUE The following is a description of the principal activities from which revenue is generated by reportable segment: Network Solutions Segment - Includes hardware and software products that enable a digital future. Services & Support Segment - Includes network design, implementation, maintenance and cloud-hosted services supporting the Company's Subscriber, Access and Aggregation, and Optical Networking Solutions. Revenue by Category In addition to the Company's reportable segments, revenue is also reported for the following three categories – Subscriber Solutions, Access & Aggregation Solutions and Optical Networking Solutions. Prior to the Business Combination with ADVA on July 15, 2022, ADTRAN reported revenue across the following three categories: (1) Access & Aggregation, (2) Subscriber Solutions & Experience and (3) Traditional & Other Products. Following the Business Combination with ADVA, we have recast these revenues such that ADTRAN’s former Access & Aggregation revenue is combined with a portion of the applicable ADVA solutions to create Access & Aggregation Solutions, ADTRAN’s former Subscriber Solutions & Experience revenue is combined with a portion of the applicable ADVA solutions to create Subscriber Solutions, and the revenue from Traditional & Other products is now included in the applicable Access & Aggregation Solutions or Subscriber Solutions category. Optical Networking Solutions is a new revenue category added to represent a meaningful portion of ADVA’s portfolio. Our Subscriber Solutions portfolio is used by service providers to terminate their access services infrastructure at the customer premises while providing an immersive and interactive experience for residential, business and wholesale subscribers. This revenue category includes hardware- and software-based products and services. These solutions include fiber termination solutions for residential, business and wholesale subscribers, Wi-Fi access solutions for residential and business subscribers, Ethernet switching and network edge virtualization solutions for business subscribers, and cloud software solutions covering a mix of subscriber types. Our Access & Aggregation Solutions are solutions that are used by communications service providers to connect residential subscribers, business subscribers and mobile radio networks to the service providers’ metro network, primarily through fiber-based connectivity. This revenue category includes hardware- and software-based products and services. Our solutions within this category are a mix of fiber access and aggregation platforms, precision network synchronization and timing solutions, and access orchestration solutions that ensure highly reliable and efficient network performance. Our Optical Networking Solutions are used by communications service providers, internet content providers and large-scale enterprises to securely interconnect metro and regional networks over fiber. This revenue category includes hardware- and software-based products and services. Our solutions within this category include open optical terminals, open line systems, optical subsystems and modules, network infrastructure assurance systems, and automation platforms that are used to build high-scale, secure and assured optical networks. The following tables disaggregate revenue by reportable segment and revenue category. Prior year amounts presented below have been reclassified to conform to the current period revenue category presentation: Three Months Ended September 30, 2022 September 30, 2021 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Subscriber Solutions $ 125,338 $ 8,337 $ 133,675 $ 42,704 $ 4,163 $ 46,867 Access & Aggregation Solutions 76,591 11,598 88,189 78,063 13,151 91,214 Optical Networking Solutions 103,011 15,834 118,845 — — — Total $ 304,940 $ 35,769 $ 340,709 $ 120,767 $ 17,314 $ 138,081 Nine Months Ended September 30, 2022 September 30, 2021 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Subscriber Solutions $ 252,899 $ 17,248 $ 270,147 $ 140,257 $ 12,232 $ 152,489 Access & Aggregation Solutions 243,396 34,877 278,273 219,768 36,589 256,357 Optical Networking Solutions 103,011 15,834 118,845 — — — Total $ 599,306 $ 67,959 $ 667,265 $ 360,025 $ 48,821 $ 408,846 The aggregate amount of transaction price allocated to remaining performance obligations that have not been satisfied as of September 30, 2022 and December 31, 2021 related to contractual maintenance agreements, contractual SaaS and subscription services, and hardware contracts that exceed one year in duration amounted to $ 276.5 milli on and $ 101.1 million, respectively. As of September 30, 2022, approximately 82 % is expected to be recognized over the next 12 months and the remainder recognized thereafter. The majority of the Company's remaining performance obligations at September 30, 2022 are related to contracts or orders that have an original expected duration of one year or less, for which the Company is electing to utilize the practical expedient available within the guidance, and are excluded from the transaction price related to these future obligations. The Company will generally satisfy the remaining performance obligations as we transfer control of the products ordered or services to our customers, excluding maintenance services, which are satisfied over time. The following table provides information about receivables, contract assets and unearned revenue from contracts with customers: As of As of (In thousands) September 30, 2022 December 31, 2021 Accounts receivable, net $ 302,401 $ 158,742 Contract assets (1) $ 1,790 $ 464 Unearned revenue $ 40,993 $ 17,737 Non-current unearned revenue $ 18,269 $ 9,271 (1) Included in other receivables on the Condensed Consolidated Balance Sheets. The Company is party to a receivables purchase agreement with a financial institution (the “Factor”). Pursuant to the terms of the arrangement, the Company, on a revolving basis, sells to the Factor certain of its accounts receivable balances without recourse. On each sale date, the Factor retains from the sale price a default reserve, up to a required balance, which are held by the Factor in a reserve account and pledged to the Company. The Factor is entitled to withdraw from the reserve account the sale price of a defaulted receivable. As of September 30, 2022, accounts receivable totaling $ 16.1 million were sold, of which $ 1.3 million was retained by the Factor in the reserve account. The balance in the reserve account is included in other assets on the Condensed Consolidated Balance Sheets. As of September 30, 2022, the Company has an allowance for doubtful accounts related to factored accounts receivable totaling $ 0.1 million. As of September 30, 2022, accounts receivables include $ 31.1 million related to the existing sale of receivables for which the transfer of the receivable has not taken place. The cost of receivables purchase agreement is included in interest expense in the Condensed Consolidated Statements of Loss and totaled $ 0.3 million for the three and nine months ended September 30, 2022. Of the outstanding unearned revenue balances as of December 31, 2021, $ 2.8 million and $ 12.3 m illion was recognized as revenue during the three and nine months ended September 30, 2022, respective ly. Of the $ 14.1 million of outstanding unearned revenue balances as of December 31, 2020, $ 2.0 million and $ 9.8 million was recognized as revenue during the three and nine months ended September 30, 2021, respectively. Accounts Receivable The Company records accounts receivable in the normal course of business as products are shipped or services are performed and invoiced, but payment has not yet been remitted by the customer. Accounts receivable balances are considered past due when payment has not been received by the date indicated on the relevant invoice or based on agreed upon terms between the customer and the Company. As of September 30, 2022 and December 31, 2021, the Company’s outstanding accounts receivable balance was $ 302.4 million, and $ 158.7 million, respectively. The Company assessed the need for an allowance for credit losses related to its outstanding accounts receivable using the historical loss-rate method as well as assessing asset-specific risks. The assessment of asset-specific risks included the evaluation of relevant available information, from internal and external sources, relating to current conditions that may affect a customer’s ability to pay, such as the customer’s current financial condition, credit rating by geographic location, as provided by a third party and/or by customer, if needed, and the overall macro-economic conditions in which the customer operates. The Company pooled assets by geographic location to determine if an allowance should be applied to its accounts receivable balance, assessing the specific country risk rating and overall economics of that particular country. If elevated risk existed, or customer specific risk indicated the accounts receivable balance was at risk, the Company further analyzed the need for an allowance related to specific accounts receivable balances. Additionally, the Company determined that significant changes to customer country risk rating from period-to-period and from the end of the prior year to the end of the current quarter would require further review and analysis by the Company. The allowance for credit losses was $ 0.2 million as of September 30, 2022 related to accounts receivable. No allowance for credit losses was recorded as of December 31, 2021 related to accounts receivable. Contract Assets The Company records contract assets when it has recognized revenue but has not yet billed the customer. As of September 30, 2022 and December 31, 2021, the Company’s outstanding contract asset balance was $ 1.8 million and $ 0.5 million, respectively, which is included in other receivables on the Consolidated Balance Sheets. The Company assessed the need for an allowance for credit losses related to its outstanding contract assets using the historical loss-rate method as well as asset-specific risks. The Company’s historical losses related to contract assets receivable have been immaterial as evidenced by historical write-offs due to collectability. Asset-specific risk included the evaluation of relevant available information, from internal and external sources, relating to current conditions that may affect a customer’s ability to pay once invoiced, such as the customer’s financial condition, credit rating by geographic location as provided by a third party and/or by customer, if needed, and the overall macro-economic conditions in which the customer operates. The Company pooled assets by geographic location to determine if an allowance should be applied to its contract asset balance, assessing the specific country risk rating and the overall economics of that particular country. If elevated risk existed, or customer specific risk indicated the contract balance was at risk, the Company further analyzed the need for an allowance related to specific customer balances. Additionally, the Company determined that significant changes to customer country risk rating from period-to-period and from the end of the prior year to the end of the current quarter would be subject to further review and analysis by the Company. No allowance for credit losses was recorded for the year ended September 30, 2022 and December 31, 2021 related to contract assets.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Income Taxes	5. INCOME TAXES The Company's effective tax rate changed from an expense of 14.1 % of pre-tax income for the three months ended September 30, 2021, to a benefit of 8.8 % of pre-tax income for the three months ended September 30, 2022 and changed from an expense of 354.5 % of pre-tax income for the nine months ended September 30, 2021, to a benefit of 9.4 % of pre-tax income for the nine months ended September 30, 2022. The change in the effective tax rate for the three and nine months ended September 30, 2022, was driven primarily by a change in our estimated tax rate as a result of the closing of the Business Combination with ADVA during the third quarter of 2022, the requirement to begin capitalizing Research and Development expenses for U.S. tax purposes beginning in 2022 as previously passed as part of the Tax Cuts and Jobs Act in December 2017 and the associated impact of those changes on our previously established valuation allowance. The Company continually reviews the adequacy of its valuation allowance and recognizes the benefits of deferred tax assets only as the assessment indicates that it is more likely than not that the deferred tax assets will be recognized in accordance with ASC 740, Income Taxes. As of September 30, 2022, the Company had net deferred tax assets totaling $ 29.2 million, and a valuation allowance totaling $ 66.1 million against those deferred tax assets. The remaining $ 36.9 million in deferred tax liabilities are primarily related to purchase price intangibles from the Business Combination closed with ADVA during the third quarter of 2022. During the nine months ended September 30, 2022, the total change in the valuation allowance against our domestic and international deferred tax assets was recorded in the amount of $ 15.8 million and $ 0.2 million, respectively. Our assessment of the realizability of our deferred tax assets includes the evaluation of historical operating results as well as the evaluation of evidence which requires significant judgment, including the evaluation of our three-year cumulative income position, future taxable income projections and tax planning strategies. Should management’s conclusion change in the future and an additional valuation allowance, or a partial or full release of the valuation allowance becomes necessary, it may have a material effect on our consolidated financial statements. Supplemental balance sheet information related to deferred tax assets (liabilities) is as follows: As of September 30, 2022 (In thousands) Deferred Tax Assets (Liabilities) Valuation Allowance Deferred Tax Liabilities, net Domestic $ 68,723 $ ( 64,054 ) $ 4,669 International ( 39,493 ) ( 2,060 ) ( 41,553 ) Total $ 29,230 $ ( 66,114 ) $ ( 36,884 ) As of December 31, 2021 (In thousands) Deferred Tax Assets Valuation Allowance Deferred Tax Assets, net Domestic $ 48,265 $ ( 48,265 ) $ — International 11,378 ( 2,299 ) 9,079 Total $ 59,643 $ ( 50,564 ) $ 9,079

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	6. STOCK-BASED COMPENSATION For the three months ended September 30, 2022 and 2021, stock-based compensation expense was $ 12.1 million and $ 1.8 million, respectively. For the nine months ended September 30, 2022 and 2021, stock-based compensation expense was $ 15.9 million and $ 5.5 million, respectively. PSUs, RSUs and Restricted Stock - ADTRAN Holdings, Inc. The following table summarizes the RSUs and restricted stock outstanding as of December 31, 2021 and September 30, 2022 and the changes that occurred during the nine months ended September 30, 2022: Number of Weighted Avg. Grant Date Fair Value Unvested RSUs and restricted stock outstanding, December 31, 2021 1,930 $ 14.11 RSUs and restricted stock granted 545 $ 19.96 RSUs and restricted stock vested ( 20 ) $ 13.67 RSUs and restricted stock forfeited ( 46 ) $ 14.18 Unvested RSUs and restricted stock outstanding, September 30, 2022 2,409 $ 17.36 During each of the nine months ended September 30, 2022 and 2021, the Company granted 0.3 million performance-based PSUs to its executive officers and certain employees. The grant-date fair value of these performance-based awards was based on the closing price of the Company’s stock on the date of grant. These awards vest over one-year , two-year and three-year periods, respectively, subject to the grantee’s continued employment, with the ability to earn shares in a range of 0 % to 142.8 % of the awarded number of PSUs based on the achievement of defined performance targets. Equity-based compensation expense with respect to these awards may be adjusted over the vesting period to reflect the probability of achievement of performance targets defined in the award agreements. Pursuant to the Business Combination, the unearned performance-based PSUs converted to time-based RSUs which was treated as an award modification during the third quarter of 2022. This resulted in incremental compensation and unrecognized compensation expense totaling $ 17.8 million of which $ 8.9 million was recognized during the three months ended September 30, 2022 and the remainder will be recognized over the remaining service period of 0.3 years. Unrecognized compensation expense will be adjusted for actual forfeitures. Pursuant to the Business Combination, 0.3 million shares of market-based PSU awards converted to time-based RSU's awards which was treated as an award modification during the third quarter of 2022. Given that the fair value of these awards after the modification was less than the fair value of the awards immediately before the modification, no incremental compensation expense was recognized. The Company continued to recognize compensation expense based on the award's original grant date fair value. As of September 30, 2022, there was $ 2.1 million of unrecognized compensation expense related to these awards which will be recognized over the weighted average remaining service period of 1.1 years. The fair value of RSUs and restricted stock is equal to the closing price of its stock on the date of grant. The fair value of PSUs with market conditions is calculated using a Monte Carlo simulation valuation method. As of September 30, 2022 , total unrecognized compensation expense related to non-vested market-based RSUs and restricted stock was approximately $ 24.6 million, which will be recognized over the remaining weighted-average period of 1.6 years. As of September 30, 2022, 3.4 million shares were available for issuance under stockholder-approved equity plans. Stock Options - ADTRAN Holdings, Inc. The following table summarizes ADTRAN Holdings, Inc. stock options outstanding as of December 31, 2021 and September 30, 2022 and the changes that occurred during the nine months ended September 30, 2022: Number of Weighted Avg. Weighted Avg. Aggregate Stock options outstanding, December 31, 2021 1,721 $ 19.37 2.4 $ 6,669 ADVA stock options replaced by ADTRAN Holdings stock options (1) 1,980 $ 11.16 Stock options exercised ( 439 ) $ 16.16 Stock options forfeited ( 12 ) $ 11.08 Stock options expired ( 70 ) $ 26.38 Stock options outstanding, September 30, 2022 3,180 $ 14.58 3.5 $ 17,839 Stock options exercisable, September 30, 2022 1,627 $ 16.85 2.0 $ 6,375 (1) Each ADVA stock option surrendered was exchanged for 0.8244 ADTRAN Holdings stock options. As of September 30, 2022 , there was $ 9.0 million of unrecognized compensation expense related to stock options which will be recognized over the remaining weighted-average period of 2.7 years. Pursuant to the Business Combination, which closed on July 15, 2022, ADVA stock option holders were entitled to have their ADVA stock options assumed by ADTRAN Holdings (applying the exchange ratio in the Business Combination Agreement), thereafter representing options to acquire stock of ADTRAN Holdings. The maximum number of shares of ADTRAN Holdings stock potentially issuable upon such assumption was 2.1 million shares. The period in which such options could be assumed ended July 22, 2022. A total of 2.0 million shares of ADTRAN Holdings stock are subject to assumed ADVA options. The determination of the fair value of stock options assumed by ADTRAN Holdings was estimated using the Monte Carlo method and is affected by its stock price, as well as assumptions regarding a number of complex and subjective variables that may have a significant impact on the fair value estimate. The stock option pricing model requires the use of several assumptions that impact the fair value estimate. These variables include, but are not limited to, the volatility of the Company's stock price and employee exercise behaviors. All of the options were previously issued at exercise prices that approximated fair market value at the date of grant. The aggregate intrinsic value of stock options represents the total pre-tax intrinsic value (the difference between ADTRAN’s closing stock price on the last trading day of the quarter and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on September 30, 2022 . The amount of aggregate intrinsic value was $ 17.8 million as of September 30, 2022 and will change based on the fair market value of ADTRAN’s stock. The total pre-tax intrinsic value of options exercised during the nine months ended September 30, 2022 was $ 3.4 million. Stock Options - ADVA Optical Networking SE The following table summarizes ADVA Optical Networking SE stock options outstanding as of July 15, 2022 (the Business Combination closing date) and September 30, 2022 and the changes that occurred between July 15, 2022 and September 30, 2022: Number of Weighted Avg. Weighted Avg. Aggregate Stock options outstanding, July 15, 2022 2,745 $ 9.09 4.6 $ 27,205 Stock options exercised ( 56 ) $ 6.79 ADVA stock options replaced by ADTRAN Holdings stock options (1) ( 2,403 ) $ 9.25 Stock options forfeited ( 4 ) $ 7.91 Stock options outstanding, September 30, 2022 282 $ 8.45 3.9 $ 2,976 Stock options exercisable, September 30, 2022 32 $ 7.72 1.2 $ 363 (1) Each ADVA stock option surrendered was exchanged for 0.8244 ADTRAN Holdings stock options. As of September 30, 2022 , there was $ 0.3 million of unrecognized compensation expense related to stock options which will be recognized over the remaining weighted-average period of 1.1 years. All of the options were previously issued at exercise prices that approximated fair market value at the date of grant. The aggregate intrinsic value of stock options represents the total pre-tax intrinsic value (the difference between ADVA's closing stock price on the last trading day of the quarter and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on September 30, 2022 . The amount of aggregate intrinsic value was $ 3.0 million as of September 30, 2022 and will change based on the fair market value of ADVA's stock. The total pre-tax intrinsic value of options exercised during the period July 15, 2022 through September 30, 2022 was $ 0.7 million.

Investments

Investments	9 Months Ended
	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Investments	7. INVESTMENTS Debt Securities and Other Investments The following debt securities and other investments were included on the Condensed Consolidated Balance Sheets and recorded at fair value: As of September 30, 2022 Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 9,358 $ — $ ( 374 ) $ 8,984 Municipal fixed-rate bonds 1,411 — ( 54 ) 1,357 Asset-backed bonds 2,988 — ( 77 ) 2,911 Mortgage/Agency-backed bonds 4,720 — ( 280 ) 4,440 U.S. government bonds 11,231 — ( 642 ) 10,589 Foreign government bonds 409 — ( 27 ) 382 Available-for-sale debt securities held at fair value $ 30,117 $ — $ ( 1,454 ) $ 28,663 As of December 31, 2021 Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 10,776 $ 6 $ ( 35 ) $ 10,747 Municipal fixed-rate bonds 1,553 2 ( 4 ) 1,551 Asset-backed bonds 322 3 ( 3 ) 322 Mortgage/Agency-backed bonds 4,754 15 ( 33 ) 4,736 U.S. government bonds 12,251 12 ( 92 ) 12,171 Foreign government bonds 543 — ( 4 ) 539 Available-for-sale debt securities held at fair value $ 30,199 $ 38 $ ( 171 ) $ 30,066 The contractual maturities related to debt securities and other investments were as follows: As of September 30, 2022 (In thousands) Corporate Municipal Asset- Mortgage/ U.S. government Foreign government bonds Less than one year $ 96 $ 525 $ — $ 182 $ — $ — One to two years 5,371 722 95 464 7,421 275 Two to three years 3,517 110 715 1,321 2,889 107 Three to five years — — 1,306 166 279 — Five to ten years — — 382 810 — — More than ten years — — 413 1,497 — — Total $ 8,984 $ 1,357 $ 2,911 $ 4,440 $ 10,589 $ 382 Actual maturities may differ from contractual maturities as some borrowers have the right to call or prepay obligations with or without call or prepayment penalties. Realized gains and losses on sales of debt securities are computed under the specific identification method. The following table presents the gross realized gains and losses related to its debt securities: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Gross realized gain on debt securities $ 1 $ 22 $ 14 $ 206 Gross realized loss on debt securities ( 116 ) ( 17 ) ( 242 ) ( 53 ) Total (loss) gain recognized, net $ ( 115 ) $ 5 $ ( 228 ) $ 153 Income generated from available-for-sale debt securities was recorded as interest and dividend income in the Condensed Consolidated Statements of Loss. No allowance for credit losses was recorded for the nine months ended September 30, 2022 and 2021 related to available-for-sale debt securities. The Company’s investment policy provides limitations for issuer concentration, which limits, at the time of purchase, the concentration in any one issuer to 5 % of the market value of its total investment portfolio. The Company did no t purchase any available-for-sale debt security with credit deterioration during the nine months ended September 30, 2022. Realized and unrealized gains and losses related to marketable equity securities were as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Realized (loss) gain on equity securities sold $ ( 1,358 ) $ — $ ( 1,675 ) $ ( 55 ) Unrealized (loss) gain on equity securities held ( 1,217 ) ( 68 ) ( 8,849 ) 2,844 Total (loss) gain recognized, net $ ( 2,575 ) $ ( 68 ) $ ( 10,524 ) $ 2,789 Income generated from marketable equity securities was recorded as interest and dividend income in the Condensed Consolidated Statements of Loss. U.S. GAAP establishes a three-level valuation hierarchy based upon observable and unobservable inputs for fair value measurement of financial instruments: • Level 2 – Significant inputs that are observable; values based on quoted prices in markets that are not active or model inputs that are observable either directly or indirectly; • Level 3 – Significant unobservable inputs; values based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs could include information supplied by investees. The Company’s cash equivalents and investments held at fair value are categorized into this hierarchy as follows: Fair Value Measurements as of September 30, 2022 Using (In thousands) Fair Value Quoted Prices Significant Significant Unobservable Inputs Cash equivalents Money market funds $ 698 $ 698 $ — $ — Available-for-sale debt securities Corporate bonds 8,984 — 8,984 — Municipal fixed-rate bonds 1,357 — 1,357 — Asset-backed bonds 2,911 — 2,911 — Mortgage/Agency-backed bonds 4,440 — 4,440 — U.S. government bonds 10,589 10,589 — — Foreign government securities 382 — 382 — Marketable equity securities Marketable equity securities – various industries 760 760 — — Deferred compensation plan assets 21,511 21,511 — — Total $ 51,632 $ 33,558 $ 18,074 $ — Fair Value Measurements as of December 31, 2021 Using (In thousands) Fair Value Quoted Prices Significant Significant Unobservable Inputs Cash equivalents Money market funds $ 652 $ 652 $ — $ — Available-for-sale debt securities Corporate bonds 10,747 — 10,747 — Municipal fixed-rate bonds 1,551 — 1,551 — Asset-backed bonds 322 — 322 — Mortgage/Agency-backed bonds 4,736 — 4,736 — U.S. government bonds 12,171 12,171 — — Foreign government bonds 539 — 539 — Marketable equity securities Marketable equity securities – various industries 12,606 12,606 — — Deferred compensation plan assets 26,935 26,935 — — Total $ 70,259 $ 52,364 $ 17,895 $ — The fair value of its Level 2 securities is calculated using a weighted average market price for each security. Market prices are obtained from a variety of industry standard data providers, large financial institutions and other third-party sources. These multiple market prices are used as inputs into a distribution-curve-based algorithm to determine the daily market value of each security.

Inventory

Inventory	9 Months Ended
	Sep. 30, 2022
Inventory Disclosure [Abstract]
Inventory	8. INVENTORY Inventory consisted of the following: As of As of (In thousands) September 30, 2022 December 31, 2021 Raw materials $ 177,554 $ 74,709 Work in process 10,625 2,143 Finished goods 227,984 63,039 Total inventory, net $ 416,163 $ 139,891 Inventory reserves are established for estimated excess and obsolete inventory equal to the difference between the cost of the inventory and the estimated net realizable value of the inventory based on estimated reserve percentages, which considers historical usage, known trends, inventory age and market conditions. As of September 30, 2022 and December 31, 2021 , inventory reserves were $ 51.3 million and $ 44.6 million, respectively.

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	9. PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment consisted of the following: As of As of (In thousands) September 30, 2022 December 31, 2021 Engineering and other equipment $ 162,445 $ 134,771 Building 80,807 68,157 Computer hardware and software 79,990 72,274 Building and land improvements 40,132 35,578 Furniture and fixtures 20,891 19,917 Land 5,298 4,575 Other assets 4,835 — Total property, plant and equipment 394,398 335,272 Less: accumulated depreciation ( 289,821 ) ( 279,506 ) Total property, plant and equipment, net $ 104,577 $ 55,766 Long-lived assets used in operations are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and the undiscounted cash flows estimated to be generated by the asset are less than the asset’s carrying value. In connection with the planned integration of information technology following the Business Combination, we determined that certain projects no longer fit our needs. As a result the Company recognized impairment charges of $ 17.0 million during the three and nine months ended September 30, 2022 related to capitalized implementation costs for a cloud computing arrangement. The impairment charges were determined based on actual costs incurred. Depreciation expense was $ 7.1 million and $ 3.0 million for the three months ended September 30, 2022 and 2021 , respectively, and $ 12.6 million and $ 9.1 million for the nine months ended September 30, 2022 and 2021, respectively, which is recorded in cost of revenue, selling, general and administrative expenses and research and development expenses in the Condensed Consolidated Statements of Loss.

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2022
Goodwill Disclosure [Abstract]
Goodwill	10. GOODWILL The changes in the carrying amount of goodwill for the nine months ended September 30, 2022 are as follows: (In thousands) Network Solutions Services & Support Total As of December 31, 2021 $ 6,568 $ 400 $ 6,968 Goodwill from Business Combination with ADVA 270,568 88,589 359,157 Foreign currency translation adjustments ( 6,220 ) ( 2,036 ) ( 8,256 ) As of September 30, 2022 $ 270,916 $ 86,953 $ 357,869 Goodwill represents the excess purchase price over the fair value of net assets acquired. We qualitatively assess the carrying value of goodwill each reporting period for events or circumstance changes that would more likely than not reduce the fair value of the reporting unit below its carrying amount. Based on its assessment of certain qualitative factors such as macro-economic conditions, industry and market considerations, costs factors and overall financial performance, management concluded that no such events or circumstance changes were identified that would suggest that the fair value of the goodwill was more likely than not greater than its carrying amount as of September 30, 2022. No impairment of goodwill was recorded during the three and nine months ended September 30, 2022 and 2021.

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2022
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	11. INTANGIBLE ASSETS Intangible assets consisted of the following: As of September 30, 2022 As of December 31, 2021 (In thousands) Weighted Average Useful Life Gross Carrying Amount Accumulated Amortization Net Book Value Gross Carrying Amount Accumulated Amortization Net Book Value Customer relationships 10.9 $ 52,139 $ ( 11,207 ) $ 40,932 $ 20,796 $ ( 9,906 ) $ 10,890 Backlog 1.4 50,966 ( 9,325 ) 41,641 — — — Developed technology 8.5 294,983 ( 11,565 ) 283,418 8,200 ( 3,683 ) 4,517 Licensed technology 9.0 5,900 ( 2,977 ) 2,923 5,900 ( 2,486 ) 3,414 Licensing agreements 8.5 560 ( 280 ) 280 560 ( 225 ) 335 Patents 7.3 500 ( 414 ) 86 500 ( 363 ) 137 Trade names 2.8 26,575 ( 2,280 ) 24,295 210 ( 210 ) — Total $ 431,623 $ ( 38,048 ) $ 393,575 $ 36,166 $ ( 16,873 ) $ 19,293 The Company evaluates the carrying value of intangible assets whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and the undiscounted cash flows estimated to be generated by the asset are less than the asset’s carrying value. Due to the current economic environment, particularly related to COVID-19, the Company assessed impairment triggers related to intangible assets during each financial period in 2022 and 2021. As a result, no quantitative impairment test of long-lived assets was performed as of September 30, 2022 and 2021 , and no impairment losses of intangible assets were recorded during the three and nine months ended September 30, 2022 and 2021. Amortization expense was $ 20.4 million and $ 1.0 million in the three months ended September 30, 2022 and 2021 , respectively, and $ 22.2 million and $ 3.1 million in the nine months ended September 30, 2022 and 2021, respectively, and was included in cost of revenue, selling, general and administrative expenses and research and development expenses in the Condensed Consolidated Statements of Loss. Estimated future amortization expense of intangible assets was as follows: As of (In thousands) September 30, 2022 2022 $ 23,691 2023 75,677 2024 53,021 2025 42,623 2026 39,505 Thereafter 159,058 Total $ 393,575

Leases

Leases	9 Months Ended
	Sep. 30, 2022
Leases [Abstract]
Leases	12. LEASES We have operating leases for office space, automobiles and various other equipment in the U.S. and in certain international locations. Other contracts, such as manufacturing agreements and service agreements, are reviewed to determine if they contain potential embedded leases. These other contracts are specifically reviewed to determine whether we have the right to substantially all of the economic benefit from the use of any specified assets or the right to direct the use of any specified assets, either of which would indicate the existence of a lease. As of September 30, 2022, our operating leases had remaining lease terms ranging from one month to seventy-eight months , some of which included options to extend the leases for up to five years , and some of which included options to terminate the leases within three months . For those leases that are reasonably assured to be renewed, we have included the option to extend as part of our right of use asset and lease liability. Supplemental balance sheet information related to operating leases is as follows: (In thousands) Classification September 30, 2022 December 31, 2021 Assets Operating lease asset Other assets $ 28,081 $ 4,922 Total lease asset $ 28,081 $ 4,922 Liabilities Current operating lease liability Accrued expenses $ 6,604 $ 1,730 Non-current operating lease liability Non-current lease obligations 21,490 3,269 Total lease liability $ 28,094 $ 4,999 Leases with an initial term of 12 months or less are not recorded on the balance sheet and the lease expense for these leases is recognized on a straight-line basis over the lease term. Lease expense rel ated to these short-term leases was less than $ 0.1 million for the three and nine months ended September 30, 2022 and 2021, and is included in cost of revenue, selling, general and administrative expenses and research and development expenses in the Condensed Consolidated Statements of Loss. Lease expense related to variable lease payments that do not depend on an index or rate, such as real estate taxes and insurance reimbursements, was $ 0.2 million and $ 0.1 million for the three months ended September 30, 2022 and 2021, respectively, and $ 0.5 million and $ 0.4 million for the nine months ended September 30, 2022 and 2021, respectively. For lease agreements entered into or reassessed after the adoption of Topic 842, we elected to not separa te lease and non-lease components. Our lease agreements do not contain any material residual value guarantees. The components of lease expense included in the Condensed Consolidated Statements of Loss were as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Selling, general and administrative expenses $ 1,444 $ 196 $ 1,704 $ 645 Research and development expenses 228 261 719 815 Cost of sales 20 14 59 38 Total operating lease expense $ 1,692 $ 471 $ 2,482 $ 1,498 As of September 30, 2022 and December 31, 2021, operating lease liabilities included on the Condensed Consolidated Balance Sheets by future maturity were as follows: (In thousands) September 30, 2022 December 31, 2021 2022 $ 2,209 $ 1,767 2023 8,421 1,419 2024 7,098 1,188 2025 5,838 710 2026 3,354 — Thereafter 5,107 — Total lease payments 32,027 5,084 Less: Interest ( 3,933 ) ( 85 ) Present value of lease liabilities $ 28,094 $ 4,999 Future operating lease payments include $ 4.5 million related to options to extend lease terms that are reasonably certain of being exercised. There are material legally binding leases that have not yet commenced. An incremental borrowing rate is used based on information available at the commencement date in determining the present value of lease payments. The incremental borrowing rate is determined on a portfolio basis by grouping leases with similar terms, as well as grouping leases based on a U.S. dollar or Euro functional currency. The following table provides information about our weighted average lease terms and weighted average discount rates: As of September 30, 2022 Weighted average remaining lease term (in years) Operating leases with USD functional currency 1.6 Operating leases with Euro functional currency 4.5 Weighted average discount rate Operating leases with USD functional currency 3.93 % Operating leases with Euro functional currency 4.05 % For the nine months ended September 30, 2022 and 2021, the Company used $ 2.3 million and $ 1.4 million of cash in operating activities related to operating leases, respectively. Net Investment in Sales-Type Leases We are the lessor in sales-type lease arrangements for network equipment, which consisted of the following: As of As of (In thousands) September 30, 2022 December 31, 2021 Current minimum lease payments receivable (1) $ 11 $ 92 Non-current minimum lease payments receivable (2) — 4 Total minimum lease payments receivable 11 96 Less: Current unearned revenue (1) 5 70 Less: Non-current unearned revenue (2) — 1 Net investment in sales-type leases $ 6 $ 25 (1) Included in other receivables on the Condensed Consolidated Balance Sheets. (2) Included in other assets on the Condensed Consolidated Balance Sheets.

Revolving Credit Agreements

Revolving Credit Agreements	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Revolving Credit Agreements	13. REVOLVING CREDIT AGREEMENTS The carrying amounts of the Company's revolving credit agreements in its Condensed Consolidated Balance Sheets were as follows: As of As of (In thousands) September 30, 2022 December 31, 2021 Wells Fargo credit agreement $ 60,000 $ — Nord/LB revolving line of credit 14,702 — Syndicated credit agreement working capital line of credit 9,801 — Wells Fargo revolving credit agreement — — Cadence revolving credit agreement — — Total revolving credit agreements $ 84,503 $ — As of September 30, 2022, the weighted average interest rate on our revolving credit agreements was 4.05 % Wells Fargo Credit Agreement On July 18, 2022, ADTRAN Holdings, Inc. and ADTRAN, Inc., as the borrower, entered into a credit agreement with a syndicate of banks, including Wells Fargo Bank, National Association, as administrative agent (“Administrative Agent”), and the other lenders named therein (the “Credit Agreement”). The Credit Agreement allows for borrowings of up to $ 100 million in aggregate principal amount, subject to being increased to up to $ 400 million in aggregate principal amount upon the Company or Borrower’s execution of a DPLTA with ADVA or a parent of ADVA, among other conditions (the “Senior Credit Facilities Increase”). On October 18, 2022, the Board of Directors of the Company. and the management board of ADVA, agreed on a final draft of a DPLTA between the Company, as the controlling company, and ADVA, as the controlled company. See Note 21 of the Notes to Condensed Consolidated Financial Statements for further information. The Credit Agreement replaced the Cadence Revolving Credit Agreement and the Wells Fargo Revolving Credit Agreement. In connection with the entry into the Credit Agreement, all outstanding borrowings under such credit agreements have been repaid and the agreements terminated. As of September 30, 2022, ADTRAN, Inc.’s borrowings under the revolving line of credit were $ 60.0 million in tranches that mature during the fourth quarter of 2022 and can either be repaid or borrowed again for a one month, three month or six month period . In addition, we may issue up to $ 25 million in letters of credit against our $ 100 million dollar total facility. As of September 30, 2022, we had a total of $ 16.0 million in letters of credit with ADTRAN, Inc. outstanding against our eligible borrowings, leaving a net amount of $ 24.0 million available for future borrowings. Any future credit extensions under the Credit Agreement are subject to customary conditions precedent. The proceeds of any loans are expected to be used for general corporate purposes and to pay a portion of the Exchange Offer consideration. All U.S. borrowings under the Credit Agreement (other than swingline loans, which will bear interest at the Base Rate (as defined below)) will bear interest, at the Company’s option, at a rate per annum equal to (A)(i) the highest of (a) the federal funds rate (i.e., for any day, the rate per annum equal to the weighted average of the rates on overnight federal funds transactions with members of the Federal Reserve System, as published by the Federal Reserve Bank of New York on the business day next succeeding such day) plus ½ of 1 %, (b) the prime commercial lending rate of the Administrative Agent, as established from time to time at its principal U.S. office (which such rate is an index or base rate and will not necessarily be its lowest or best rate charged to its customers or other banks), and (c) the daily Adjusted Term SOFR (as defined in the Credit Agreement) for a one-month tenor plus 1 %, plus (ii) the applicable rate, ranging from 0.5 % to 1.25 % (the “Base Rate”), or (B) the sum of the Adjusted Term SOFR (as defined in the Credit Agreement) plus the applicable rate, ranging from 1.4 % to 2.15 %, provided that such sum is subject to a 0.0 % floor (such loans utilizing this interest rate, “SOFR Loans”). All E.U. borrowings under the Credit Agreement (other than swingline loans) will bear interest at a rate per annum equal to the sum of the Euro Interbank Offered Rate as administered by the European Money Markets Institute (or a comparable or successor administrator approved by the Administrative Agent) plus the applicable rate, ranging from 1.5 % to 2.25 %, provided that such sum is subject to a 0.0 % floor (such loans utilizing this interest rate, “EURIBOR Loans”). The applicable rate is based on the consolidated net leverage ratio of the Company and its subsidiaries as determined pursuant to the terms of the Credit Agreement. Default interest is 2.00 % per annum in excess of the rate otherwise applicable in the case of any overdue principal or any other overdue amount. In addition to paying interest on outstanding principal under the Credit Agreement, the Company is required to pay a commitment fee to the lenders under the Credit Agreement in respect of unutilized revolving loan commitments and an additional commitment ticking fee at a rate of 0.25 % on the commitment amounts of each lender until the earliest of (i) the date of the Senior Credit Facilities Increase, (ii) the Company’s voluntary termination of the credit facility commitment, and (iii) December 31, 2023. The Company is also required to pay a participation fee to the Administrative Agent for the account of each lender with respect to the Company’s participations in letters of credit at the then applicable rate for SOFR Loans. The Credit Agreement permits the Company to prepay any or all of the outstanding loans or to reduce the commitments under the Credit Agreement without incurring premiums or penalties (except breakage costs with respect to SOFR Loans and EURIBOR Loans). The Credit Agreement contains customary affirmative and negative covenants, including incurrence covenants and certain other limitations on the ability of the Company and the Company’s subsidiaries to incur additional debt, guarantee other obligations, grant liens on assets, make investments, dispose of assets, pay dividends or other payments on capital stock, make restricted payments, engage in mergers or consolidations, engage in transactions with affiliates, modify its organizational documents, and enter into certain restrictive agreements. It also contains customary events of default (subject to customary cure periods and materiality thresholds). Furthermore, the Credit Agreement requires that the consolidated total net leverage ratio (as defined in the Credit Agreement) of the Company and its subsidiaries tested on the last day of each fiscal quarter not exceed 3.25 to 1.0 through September 30, 2024 and 2.75 to 1.00 from December 31, 2024 and thereafter, subject to certain exceptions. The Credit Agreement also requires that the consolidated interest coverage ratio (as defined in the Credit Agreement) of the Company and its subsidiaries tested on the last day of each fiscal quarter not fall below 3.00 to 1.00. As of September 30, 2022, the Company was in compliance with all material covenants. The Credit Agreement matures in July 2027 but provides the Company with an option to request extensions subject to customary conditions. Finally, pursuant to a Collateral Agreement, dated as of July 18, 2022, among the Company, ADTRAN, Inc. and the Administrative Agent, ADTRAN, Inc.’s obligations under the Credit Agreement are secured by substantially all of the assets of ADTRAN, Inc. and the Company. In addition, the Company has guaranteed ADTRAN, Inc.’s obligations under the Credit Agreement pursuant to a Guaranty Agreement, dated as of July 18, 2022, by ADTRAN, Inc. and the Company in favor of the Administrative Agent. Nord/LB Revolving Line of Credit August 8, 2022, ADVA entered into a $ 14.7 million revolving line of credit with Norddeutsche Landesbark - Girozentrale (Nord/LB) that bears interest of Euro Short Term Rate + 1.4 % and which matures in August 2023 . During the term of the loan, ADVA is obligated to maintain an adjusted net debt to cover ratio that is equal to or less than 2.75 . As of September 30, 2022, The Company was in compliance with the adjusted net debt to cover ratio. The revolving line of credit grants Nord/LB a lien on assets of any kind which come into the possession of ADVA. Assets of any kind includes goods, foreign exchange, securities including interest, annuity and profit notes, collective securities deposits, subscription rights, checks, bills of exchange, bills of lading, storage and loading slips. As of September 30, 2022, ADVA’s borrowings under the revolving line of credit were $ 14.7 million, with no amounts available for future borrowings. Syndicated Credit Agreement Working Capital Line of Credit In September 2018, ADVA entered into a syndicated credit agreement with Bayerische Landesbank and Deutsche Bank AG Branch German Business to borrow up to $ 9.8 million as part of a working capital line of credit. The interest rate for the working capital line of credit is adjusted periodically based on a defined leverage ratio and is currently EURIBOR plus 1.35 % as of September 30, 2022. The working capital line of credit matures in September 2023. As of September 30, 2022, borrowings under the working capital line of credit totaled $ 9.8 million, with no amounts available for future borrowings. Prior Wells Fargo Revolving Credit Agreement On April 1, 2022, ADTRAN, Inc. entered into a Credit Agreement and related Revolving Line of Credit Note (together, the “Prior Wells Revolving Credit Agreement”) in favor of Wells Fargo Bank, National Association, as lender (the “Wells Lender”). The Wells Revolving Credit Agreement provided the Company with a $ 25.0 million secured revolving credit facility. During the first nine months of 2022, the Company made draws totaling $ 10.0 million under the Prior Wells Revolving Credit Agreement all of which had been repaid as of September 30, 2022. The Wells Fargo Credit Agreement replaced the Prior Wells Fargo Revolving Credit Agreement and all outstanding borrowings have been repaid and the prior agreement was terminated. Prior Cadence Revolving Credit Agreement On May 19, 2022, ADTRAN, Inc., as borrower, modified its Revolving Credit and Security Agreement and related Promissory Note (together, the “Cadence Revolving Credit Agreement”) with Cadence Bank, N.A., as lender (the “Cadence Lender”). The modified Prior Cadence Revolving Credit Agreement provided the Company with a $ 25.0 million secured revolving credit facility. During the first nine months of 2022, the Company made draws totaling $ 18.0 million under the Prior Cadence Revolving Credit Agreement all of which had been repaid as of September 30, 2022. The Wells Fargo Credit Agreement replaced the Prior Cadence Revolving Credit Agreement and all outstanding borrowings have been repaid and the prior agreement was terminated.

Notes Payable

Notes Payable	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Notes Payable	14. NOTES PAYABLE The carrying amounts of the Company's notes payable in its Condensed Consolidated Balance Sheets were as follows: Fair Value as of Carrying Value as of Carrying Value as of (In thousands) September 30, 2022 September 30, 2022 December 31, 2021 Syndicated credit agreement note payable $ 29,611 $ 29,782 $ — Deutsche Bank term loan — — — Total Notes Payable $ 29,611 $ 29,782 $ — Syndicated Credit Agreement Note Payable In September 2018, ADVA entered into a syndicated credit agreement with Bayerische Landesbank and Deutsche Bank AG Branch German Business to borrow $ 63.7 million. The interest rate for the note payable is adjusted periodically based on a defined leverage ratio and is currently EURIBOR plus 1.35 % as of September 30, 2022. The note payable matures in September 2023. Deutsche Bank Term Loan In October 2019, ADVA entered into a $ 9.8 million revolving line of credit with Deutsche Bank that bears interest of EURIBOR plus 1.1 %. The line of credit matured in September 2022 and was repaid as of September 30, 2022.

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2022
Retirement Benefits [Abstract]
Employee Benefit Plans	15. EMPLOYEE BENEFIT PLANS We maintain defined benefit pension plans covering employees in certain foreign countries. Pension benefit plan obligations are based on various assumptions used by its actuaries in calculating these amounts. These assumptions include discount rates, compensation rate increases, expected return on plan assets, retirement rates and mortality rates. Actual results that differ from the assumptions and changes in assumptions could affect future expenses and obligations. The Company's net pension liability totaled $ 16.2 million and $ 11.4 million as of September 30, 2022 and December 31, 2021, respectively. The following table summarizes the components of net periodic pension cost related to a defined benefit pension plan covering employees in certain foreign countries: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Service cost $ 478 $ 307 $ 981 $ 931 Interest cost 204 84 638 257 Expected return on plan assets ( 465 ) ( 460 ) ( 1,384 ) ( 1,396 ) Amortization of actuarial losses 81 272 254 825 Net periodic pension cost $ 298 $ 203 $ 489 $ 617 The components of net periodic pension cost, other than the service cost component, are included in other income, net in the Condensed Consolidated Statements of Loss. Service cost is included in cost of revenue, selling, general and administrative expenses and research and development expenses in the Condensed Consolidated Statements of Loss. The Company made contributions to the defined benefit pension plans totaling $ 1.2 million during the nine months ending September 30, 2022. Contributions to the defined benefit pension plans for the remainder of 2022 will be limited to benefit payments to retirees which are paid out of the operating cash flows of the Company and are expected to be approximately $ 0.6 million.

Equity

Equity	9 Months Ended
	Sep. 30, 2022
Equity [Abstract]
Equity	16. EQUITY Non-Controlling Interest Non-controlling interest represents the equity interest in ADVA held by holders other than the Company. On July 15, 2022, upon the closing of the Business Combination, the ADVA stockholders ’ equity ownership percentage in ADVA was 34.57 %. The Company has consolidated the financial position and results of operations of ADVA and reflected the proportionate interest held by the ADVA stockholders as non-controlling interest in the accompanying Condensed Consolidated Balance Sheet. As of September 30, 2022, the ADVA stockholders ’ equity ownership percentage in ADVA was 34.65 %. Stock Repurchase Program During the nine months ended September 30, 2022 , the Company did no t repurchase any shares of Company Common Stock and there is no current authorization to repurchase Company Common Stock. Accumulated Other Comprehensive Loss The following tables present the changes in accumulated other comprehensive loss, net of tax, by component: Three Months Ended September 30, 2022 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance as of June 30, 2022 $ ( 1,476 ) $ ( 5,713 ) $ ( 9,892 ) $ 385 $ ( 16,696 ) Other comprehensive loss before ( 254 ) — ( 23,172 ) — ( 23,426 ) Amounts reclassified from accumulated other ( 142 ) ( 118 ) — — ( 260 ) Net current period other comprehensive (loss) income ( 396 ) ( 118 ) ( 23,172 ) — ( 23,686 ) Less: Comprehensive Loss attributable to non-controlling interest, net of tax — — ( 94 ) — ( 94 ) Balance as of September 30, 2022 $ ( 1,872 ) $ ( 5,831 ) $ ( 32,970 ) $ 385 $ ( 40,288 ) Three Months Ended September 30, 2021 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance as of June 30, 2021 $ ( 255 ) $ ( 9,310 ) $ ( 3,960 ) $ 385 $ ( 13,140 ) Other comprehensive loss before ( 29 ) — ( 1,389 ) — ( 1,418 ) Amounts reclassified from accumulated other ( 32 ) 124 — — 92 Net current period other comprehensive (loss) income ( 61 ) 124 ( 1,389 ) — ( 1,326 ) Balance as of September 30, 2021 $ ( 316 ) $ ( 9,186 ) $ ( 5,349 ) $ 385 $ ( 14,466 ) Nine Months Ended September 30, 2022 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total As of December 31, 2021 $ ( 552 ) $ ( 5,613 ) $ ( 6,134 ) $ 385 $ ( 11,914 ) Other comprehensive loss before ( 1,818 ) — ( 26,930 ) — ( 28,748 ) Amounts reclassified from accumulated other 498 ( 218 ) — — 280 Net current period other comprehensive loss ( 1,320 ) ( 218 ) ( 26,930 ) — ( 28,468 ) Less: Comprehensive Loss attributable to non-controlling interest, net of tax — — ( 94 ) — ( 94 ) As of September 30, 2022 $ ( 1,872 ) $ ( 5,831 ) $ ( 32,970 ) $ 385 $ ( 40,288 ) Nine Months Ended September 30, 2021 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total As of December 31, 2020 $ 32 $ ( 9,621 ) $ ( 2,435 ) $ 385 $ ( 11,639 ) Other comprehensive loss before ( 358 ) — ( 2,914 ) — ( 3,272 ) Amounts reclassified from accumulated other 10 435 — — 445 Net current period other comprehensive (loss) income ( 348 ) 435 ( 2,914 ) — ( 2,827 ) As of September 30, 2021 $ ( 316 ) $ ( 9,186 ) $ ( 5,349 ) $ 385 $ ( 14,466 ) The following tables present the details of reclassifications out of accumulated other comprehensive loss: Three Months Ended September 30, 2022 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized loss on sales of securities $ 187 Net investment (loss) gain Defined benefit plan adjustments – actuarial loss 171 (1) Total reclassifications for the period, before tax 358 Tax benefit ( 98 ) Total reclassifications for the period, net of tax $ 260 (1) A part of the computation of net periodic pension cost, which is included in other income, net in the Condensed Consolidated Statements of Loss. Three Months Ended September 30, 2021 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized loss on sales of securities $ 42 Net investment (loss) gain Defined benefit plan adjustments – actuarial gain ( 180 ) (1) Total reclassifications for the period, before tax ( 138 ) Tax expense 46 Total reclassifications for the period, net of tax $ ( 92 ) (1) A part of the computation of net periodic pension cost, which is included in other income, net in the Condensed Consolidated Statements of Loss. Nine Months Ended September 30, 2022 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized gain on sales of securities $ ( 655 ) Net investment (loss) gain Defined benefit plan adjustments – actuarial loss 316 (1) Total reclassifications for the period, before tax ( 339 ) Tax expense 59 Total reclassifications for the period, net of tax $ ( 280 ) (1) A part of the computation of net periodic pension cost, which is included in other income, net in the Condensed Consolidated Statements of Loss. Nine Months Ended September 30, 2021 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized gain on sales of securities $ ( 13 ) Net investment (loss) gain Defined benefit plan adjustments – actuarial gain ( 630 ) (1) Total reclassifications for the period, before tax ( 643 ) Tax expense 198 Total reclassifications for the period, net of tax $ ( 445 ) (1) A part of the computation of net periodic pension cost, which is included in other income, net in the Condensed Consolidated Statements of Loss. The following tables present the tax effects related to the change in each component of other comprehensive loss: Three Months Ended Three Months Ended September 30, 2022 September 30, 2021 (In thousands) Before-Tax Tax Net-of-Tax Before-Tax Tax Net-of-Tax Unrealized loss on available-for-sale $ ( 334 ) $ 80 $ ( 254 ) $ ( 38 ) $ 9 $ ( 29 ) Reclassification adjustment for amounts related to ( 187 ) 45 ( 142 ) ( 42 ) 10 ( 32 ) Reclassification adjustment for amounts related to ( 171 ) 53 ( 118 ) 180 ( 56 ) 124 Foreign currency translation adjustments ( 23,172 ) — ( 23,172 ) ( 1,389 ) — ( 1,389 ) Total Other Comprehensive Loss $ ( 23,864 ) $ 178 $ ( 23,686 ) $ ( 1,289 ) $ ( 37 ) $ ( 1,326 ) Nine Months Ended Nine Months Ended September 30, 2022 September 30, 2021 (In thousands) Before-Tax Tax Net-of-Tax Before-Tax Tax Net-of-Tax Unrealized loss on available-for-sale $ ( 2,392 ) $ 574 $ ( 1,818 ) $ ( 471 ) $ 113 $ ( 358 ) Reclassification adjustment for amounts related to 655 ( 157 ) 498 13 ( 3 ) 10 Reclassification adjustment for amounts related to ( 316 ) 98 ( 218 ) 630 ( 195 ) 435 Foreign currency translation adjustments ( 26,930 ) — ( 26,930 ) ( 2,914 ) — ( 2,914 ) Total Other Comprehensive Loss $ ( 28,983 ) $ 515 $ ( 28,468 ) $ ( 2,742 ) $ ( 85 ) $ ( 2,827 )

Loss Per Share

Loss Per Share	9 Months Ended
	Sep. 30, 2022
Earnings Per Share [Abstract]
Loss Per Share	17. LOSS PER SHARE The calculation of basic and diluted loss per share is as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands, except per share amounts) 2022 2021 2022 2021 Numerator Net loss attributable to ADTRAN Holdings, Inc. $ ( 41,934 ) $ ( 10,427 ) $ ( 40,918 ) $ ( 4,445 ) Denominator Weighted average number of shares – basic 73,036 48,609 57,175 48,470 Effect of dilutive securities Stock options — — — — PSUs, RSUs and restricted stock — — — — Weighted average number of shares – diluted 73,036 48,609 57,175 48,470 Loss per share attributable to ADTRAN Holdings, Inc. – basic $ ( 0.57 ) $ ( 0.21 ) $ ( 0.72 ) $ ( 0.09 ) Loss per share attributable to ADTRAN Holdings, Inc. – diluted $ ( 0.57 ) $ ( 0.21 ) $ ( 0.72 ) $ ( 0.09 ) For the three months ended September 30, 2022 and 2021, four thousand and less than one thousand shares, respectively, and for the nine months ended September 30, 2022 and 2021, four thousand shares of unvested PSUs, RSUs and restricted stock were excluded from the calculation of diluted earnings per share due to their anti-dilutive effect. For the three months ended September 30, 2022 and 2021, 0.1 million and 0.2 million stock options, respectively, and for the nine months ended September 30, 2022 and 2021, 0.2 million and 0.4 million stock options, respectively, were outstanding but were not included in the computation of diluted earnings per share. These stock options were excluded because their exercise prices were greater than the average market price of the common shares during the applicable period, making them anti-dilutive under the treasury stock method.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2022
Segment Reporting [Abstract]
Segment Information	18. SEGMENT INFORMATION The chief operating decision maker regularly reviews the Company’s financial performance based on two reportable segments: (1) Network Solutions and (2) Services & Support. The Network Solutions segment includes hardware and software products that enable a digital future. The Company's cloud-managed Wi-Fi gateways, virtualization software, and switches provide a mix of wired and wireless connectivity at the customer premises. In addition, its Carrier Ethernet products support a variety of applications at the network edge ranging from mobile backhaul to connecting enterprise customers (“Subscriber Solutions"). The Company's portfolio includes products for multi-gigabit service delivery over fiber or alternative media to homes and businesses. The Company supports traditional chassis-based network solutions, such as the Total Access 5000 and hiX 5600. The Company accelerates the industry’s transition to open, disaggregated fiber access solutions with our SDX Series. Data is aggregated via its XG400 product family and synchronized by its Oscilloquartz offerings (“Access and Aggregation Solutions”). All resulting traffic requires transport through fiber-based networks as supported by its FSP 3000 and MicroMux product families while the underlying infrastructure is monitored by its ALM product offering (“Optical Networking Solutions”). The Company's customers can use its Mosaic and Ensemble software suites to manage and orchestrate its complete portfolio of subscriber solutions, access and aggregation solutions and optical networking solutions. The Mosaic and Ensemble software suites includes a mix of orchestration and management solutions that simplify the deployment and virtualization of next generation fiber networks. The Services & Support segment offers a comprehensive portfolio of network design, implementation, maintenance and cloud-hosted services supporting its Subscriber, Access and Aggregation, and Optical Networking Solutions. These services assist operators in the deployment of multi-vendor networks while reducing their cost to maintain these networks. The cloud-hosted services include a suite of SaaS applications under its Mosaic One platform that manages end-to-end network and service optimization for both fiber access infrastructure and mesh Wi-Fi connectivity. We back these services with a global support organization that offers on-site and off-site support services with varying SLAs. By pairing the Company's network solutions with its global services and support organization, customers can turn to the Company as their single turnkey partner to assist with the deployment and maintenance of modern fiber-based networks to connect homes, businesses and datacenters with the metro or network core. The performance of these segments is evaluated based on revenue, gross profit and gross margin; therefore, selling, general and administrative expenses, research and development expenses, interest and dividend income, interest expense, net investment (loss) gain, other income, net and income tax benefit (expense) are reported on a Company-wide basis only. There is no inter-segment revenue. Asset information by reportable segment is not produced and, therefore, is not reported. The following tables present information about the revenue and gross profit of its reportable segments: Three Months Ended September 30, 2022 September 30, 2021 (In thousands) Revenue Gross Profit Revenue Gross Profit Network Solutions $ 304,940 $ 82,334 $ 120,767 $ 39,738 Services & Support 35,769 20,693 17,314 7,935 Total $ 340,709 $ 103,027 $ 138,081 $ 47,673 Nine Months Ended September 30, 2022 September 30, 2021 (In thousands) Revenue Gross Profit Revenue Gross Profit Network Solutions $ 599,306 $ 186,126 $ 360,025 $ 143,981 Services & Support 67,959 33,723 48,821 19,961 Total $ 667,265 $ 219,849 $ 408,846 $ 163,942 Revenue by Category In addition to its reportable segments, revenue is also reported for the following three categories – Subscriber Solutions, Access & Aggregation Solutions, and Optical Networking Solutions. Prior to the Business Combination with ADVA on July 15, 2022, ADTRAN reported revenue across the following three categories: (1) Access & Aggregation, (2) Subscriber Solutions & Experience and (3) Traditional & Other Products. Following the Business Combination with ADVA, we have recast these revenues such that ADTRAN’s former Access & Aggregation revenue is combined with a portion of the applicable ADVA solutions to create Access & Aggregation Solutions, ADTRAN’s former Subscriber Solutions & Experience revenue is combined with a portion of the applicable ADVA solutions to create Subscriber Solutions, and the revenue from Traditional & Other products is now included in the applicable Access & Aggregation Solutions or Subscriber Solutions category. Optical Networking Solutions is a new revenue category added to represent a meaningful portion of ADVA’s portfolio. Our Subscriber Solutions portfolio is used by service providers to terminate their access services infrastructure at the customer premises while providing an immersive and interactive experience for residential, business and wholesale subscribers. This revenue category includes hardware- and software-based products and services. These solutions include fiber termination solutions for residential, business and wholesale subscribers, Wi-Fi access solutions for residential and business subscribers, Ethernet switching and network edge virtualization solutions for business subscribers, and cloud software solutions covering a mix of subscriber types. Our Access & Aggregation Solutions are solutions that are used by communications service providers to connect residential subscribers, business subscribers and mobile radio networks to the service providers’ metro network, primarily through fiber-based connectivity. This revenue category includes hardware- and software-based products and services. Our solutions within this category are a mix of fiber access and aggregation platforms, precision network synchronization and timing solutions, and access orchestration solutions that ensure highly reliable and efficient network performance. Our Optical Networking Solutions are used by communications service providers, internet content providers and large-scale enterprises to securely interconnect metro and regional networks over fiber. This revenue category includes hardware- and software-based products and services. Our solutions within this category include open optical terminals, open line systems, optical subsystems and modules, network infrastructure assurance systems, and automation platforms that are used to build high-scale, secure and assured optical networks. The table below presents revenue information by category. Prior year amounts presented below have been reclassified to conform to the current period revenue category presentation: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Subscriber Solutions $ 133,675 $ 46,867 $ 270,147 $ 152,489 Access & Aggregation Solutions 88,189 91,214 278,273 256,357 Optical Networking Solutions 118,845 — 118,845 — Total $ 340,709 $ 138,081 $ 667,265 $ 408,846 Revenue by Geographic Area The following table presents revenue information by geographic area: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 United States $ 169,669 $ 91,868 $ 374,470 $ 273,009 United Kingdom 64,234 12,504 123,477 34,006 Germany 46,569 17,782 71,945 50,737 Other international 60,237 15,927 97,373 51,094 Total $ 340,709 $ 138,081 $ 667,265 $ 408,846

Liability for Warranty Returns

Liability for Warranty Returns	9 Months Ended
	Sep. 30, 2022
Product Warranties Disclosures [Abstract]
Liability for Warranty Returns	19. LIABILITY FOR WARRANTY RETURNS The Company's products generally include warranties of 90 days to five years for product defects. The Company accrues for warranty returns at the time of product shipment based on its historical return rate and estimate of the cost to repair or replace the defective products. The Company engages in extensive product quality programs and processes, including actively monitoring and evaluating the quality of its component suppliers. The increasing complexity of the Company's products may cause warranty incidences, when they arise, to be more costly. Estimates regarding future warranty obligations may change due to product failure rates, material usage and other rework costs incurred in correcting a product failure. In addition, from time to time, specific warranty accruals may be recorded if unforeseen problems arise. Should the Company's actual experience relative to these factors be worse than its estimates, the Company will be required to record additional warranty expense. The liability for warranty obligations totaled $ 8.6 million and $ 5.4 million as of September 30, 2022 and December 31, 2021 , respectively, and is included in accrued expenses and other liabilities in the Condensed Consolidated Balance Sheets. During the three months ended September 30, 2021, the Company had a net reversal of prior provisions related to warranty expirations the impact of which is reflected in the table below. The warranty expense and write-off activity for the three and nine months ended September 30, 2022 and 2021 are summarized as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Balance at beginning of period $ 4,842 $ 5,997 $ 5,403 $ 7,146 Plus: ADVA acquisition 3,756 — 3,756 — Plus: Amounts charged to cost and expenses 616 472 1,727 253 Less: Deductions ( 613 ) ( 822 ) ( 2,285 ) ( 1,752 ) Balance at end of period $ 8,601 $ 5,647 $ 8,601 $ 5,647

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	20. COMMITMENTS AND CONTINGENCIES Legal Maters From time to time we are subject to or otherwise involved in various lawsuits, claims, investigations and legal proceedings that arise out of or are incidental to the conduct of our business (collectively, “Legal Matters”), including those relating to employment matters, patent rights, regulatory compliance matters, stockholder claims, and contractual and other commercial disputes. Such Legal Matters, even if not meritorious, could result in the expenditure of significant financial and managerial resources. Additionally, an unfavorable outcome in a legal matter, including in a patent dispute, could require the Company to pay damages, entitle claimants to other relief, such as royalties, or could prevent the Company from selling some of its products in certain jurisdictions. At this time, we are unable to predict the outcome of or estimate the possible loss or range of loss, if any, associated with such legal matters. Performance Bonds C ertain contracts, customers and jurisdictions in which we do business require us to provide various guarantees of performance such as bid bonds, performance bonds and customs bonds. As of September 30, 2022 and December 31, 2021, we had commitments related to these bonds totaling $ 21.1 million and $ 22.9 million, respectively, which expire at various dates through April 2025 . In general we would only be liable for the amount of these guarantees in the event of default under each contract, the probability of which we believe is remote. Purchase Commitments We purchase components from a variety of suppliers and use contract manufacturers to provide manufacturing services for our products. Our inventory purchase commitments are for short-term product manufacturing requirements as well as for commitments to suppliers to secure manufacturing capacity. Certain of our inventory purchase commitments with contract manufacturers and suppliers relate to arrangements to secure supply and pricing for certain product components for multi-year periods. As of September 30, 2022, purchase commitments totaled $ 454.1 million. Investment Commitment We have committed to invest up to an aggregate of $ 5.0 million in a private equity fund, of which $ 4.9 million has been invested as of September 30, 2022 .

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2022
Subsequent Events [Abstract]
Subsequent Events	21. SUBSEQUENT EVENTS Dividend Approval On November 7, 2022, the Company announced that its Board of Directors declared a quarterly cash dividend of $ 0.09 per common share to be paid to the Company’s stockholders of record as of the close of business on November 22, 2022. The payment date will be December 6, 2022 in the aggregate amount of approximately $ 7.0 million. Assumed ADVA Options Pursuant to the Business Combination which closed on July 15, 2022 , ADVA stock option holders were entitled to have their ADVA stock options assumed by ADTRAN Holdings, Inc. (applying the exchange ratio in the Business Combination Agreement), thereafter representing options to acquire stock of ADTRAN Holdings, Inc. The period in which such options could be assumed ended July 22, 2022. However, that period was subsequently extended and a total of 0.1 million shares of ADTRAN Holdings, Inc. stock are subject to additional assumed ADVA options. The fair value of the stock options assumed by ADTRAN Holdings, Inc. will be estimated using a Black-Scholes model. The valuation of this component of consideration is not yet complete. Approval of Proposed Domination and Profit and Loss Transfer Agreement On October 18, 2022, the Board of Directors of the Company and the management board of ADVA, agreed on a final draft of a domination and profit and loss transfer agreement (the “DPLTA”) between the Company, as the controlling company, and ADVA, as the controlled company. The parties’ execution of the DPLTA remains subject to the approval of the DPLTA by shareholders of ADVA with 75 % of the votes cast in an extraordinary general meeting, which is scheduled to be held on November 30, 2022. The Company currently holds 33,957,538 shares of ADVA, representing 65.35 % of ADVA’s outstanding shares as of September 30, 2022. Subject to the approval of the DPLTA shareholders and the subsequent registration of the DPLTA with the commercial register of the local court at ADVA’s registered offices, the Company will offer, at the election of each shareholder of ADVA (other than the Company), (i) to acquire the shares of such shareholder for a compensation ( Abfindung ) of EUR 17.21 per share pursuant to Sec. 305 German Stock Corporation Akt ( Aktiengesetz, “AktG”), or (ii) to pay such shareholder a fixed annual recurring compensation payment ( Ausgleichszahlung ) pursuant to Sec. 304 AktG in an amount of EUR 0.59 (EUR 0.52 net under the current taxation regime), subject to adjustment prior to execution of the DPLTA due to changes in interest rates and borrowing costs prior to November 30, 2022, which is the reference date for the valuation of ADVA shares ("Annual Recurring Compensation"). The amount of the Annual Recurring Compensation payment of EUR 0.59 (EUR 0.52 net) is determined on the basis of a rounded annuity interest rate ( Verrentungszinssatz ) of 3.00 % and still subject to an adjustment in case of a change of interest rates and borrowing costs prior to November 30, 2022 which is the reference date for the valuation. An increase of borrowing costs could lead to an increase of the Annual Recurring Compensation payment. The potential increase ranges from EUR 0.62 (EUR 0.54 net), if the annuity interest rate is increased by 25 basis points to 3.25 %, up to an Annual Recurring Compensation payment at the amount of EUR 1.00 (EUR 0.87 net), if the annuity interest rate is increased by 250 basis points to 5.50 %. Board Approval Purchase of ADVA Common Stock On October 18, 2022, the Company's Board of Directors authorized the Company to purchase additional shares of ADVA through open market purchases not to exceed 15,346,544 shares. Foreign Currency Hedging Agreement On November 3, 2022, the Company entered into a Euro/U.S. dollar cross-currency swap arrangement (the “Swap”) with Wells Fargo Bank, N.A. (the “Hedge Counterparty”). The Swap, which is governed by the provisions of an ISDA Master Agreement (including schedules thereto and transaction confirmations that supplement such agreement) entered into between the Company and the Hedge Counterparty, enable the Company to convert a portion of its Euro denominated payment obligations under the proposed DPLTA into U.S. Dollars. Under the Swap, the Company will exchange an aggregate notional amount of $ 160.0 million U.S. dollars for Euros at a daily fixed forward rate ranging from $ 0.98286 to $ 1.03290 . The aggregate amount of $ 160.0 million will be divided into eight quarterly tranches of $ 20.0 million. The Company, at its sole discretion, may exchange all or part of each tranche on any given day within the applicable quarter; provided, however, that it must exchange the full tranche by the end of such quarter. The Swap may be accelerated or terminated early for a number of reasons, including but not limited to (i) non-payment by the Company or the Hedge Counterparty, (ii) breach of representation or warranty or covenant by either party or (iii) insolvency or bankruptcy of either party.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited Condensed Consolidated Financial Statements of ADTRAN Holdings, Inc. and its subsidiaries have been prepared pursuant to the rules and regulations of 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	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 allowance for credit losses on accounts receivable and contract assets, 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), supply chain constraints, inflationary pressures, the energy crisis, currency fluctuations and political tensions as of September 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 and inflationary pressures could result in further impacts to the Company's consolidated financial statements in future reporting periods.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements 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. The Company early adopted ASU 2021-08 on July 1, 2022 and the standard was applied retrospectively beginning with January 1, 2022. The effect of the adoption of this standard on the Company's Condensed Consolidated Financial Statements as of the date of this report is included in Note 2 of the Notes to Condensed Consolidated Financial Statements .
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted There are currently no accounting pronouncements not yet adopted that had a material effect on the Condensed Consolidated Financial Statements.

Business Combination (Tables)

Business Combination (Tables)	9 Months Ended
	Sep. 30, 2022
Business Combinations [Abstract]
Summary of Purchase Price for Business Combination	The following table summarizes the purchase price for the ADVA business combination: (In thousands, except shares, share price and exchange ratio) Purchase Price ADVA shares exchanged 33,957,538 Exchange ratio 0.8244 ADTRAN Holdings, Inc. shares issued 27,994,595 ADTRAN Holdings, Inc. share price on July 15, 2022 $ 20.20 Purchase price paid for ADVA shares $ 565,491 Equity compensation (1) $ 12,769 Total purchase price $ 578,260 (1) Represents the portion of replacement share-based payment awards that relates to pre-combination vesting.
Summary of Purchase Price Allocation of Assets Acquired and Liabilities Assumed	The following table summarizes the preliminary purchase price allocation for each major class of assets acquired and liabilities assumed in the acquisition of ADVA (in thousands): (In thousands) Total purchase price $ 578,260 Non-controlling interest $ 316,415 Net Assets: Cash and cash equivalents $ 44,003 Accounts receivable 114,659 Other receivables 1,457 Inventory 200,532 Prepaid expenses and other current assets 29,474 Property plant and equipment 52,796 Deferred tax assets 1,599 Intangibles 405,385 Other non-current assets 30,588 Accounts payable ( 98,587 ) Current unearned revenue ( 26,047 ) Accrued expenses and other liabilities ( 59,600 ) Current portion of notes payable ( 25,254 ) Income tax payable ( 1,400 ) Non-current unearned revenue ( 11,498 ) Pension liability ( 6,820 ) Other non-current liabilities ( 6,094 ) Non-current portion of revolving credit agreements and notes payable ( 15,250 ) Non-current lease obligations ( 20,046 ) Deferred tax liabilities ( 74,379 ) Total net assets acquired $ 535,518 Goodwill $ 359,157
Summary of Fair Value of Intangible Assets Acquired	The fair value of the intangible assets acquired as of the acquisition date: (In thousands) Estimated-average useful life (in years) (1) Fair value Income Statement Amortization Classification Developed technology 8.5 $ 293,530 Cost of revenue - Network Solutions Backlog 1.4 52,165 Cost of revenue - Network Solutions and Services & Support Customer relationships 10.5 32,704 Selling, general and administrative expenses Trade name 2.8 26,986 Selling, general and administrative expenses Total $ 405,385 (1) Determination of the weighted average period of the individual categories of intangible assets was based on the nature of the applicable intangible asset and the expected future cash flows to be derived from the intangible asset. Amortization of intangible assets with definite lives is recognized over the period of time the assets are expected to contribute to future cash flows.
Summary of Unaudited Pro Forma Financial Information	The unaudited pro forma financial information in the table below summarizes the combined results of operations for ADTRAN and ADVA as though the Business Combination had occurred on January 1, 2021. Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Revenue $ 368,192 $ 317,067 $ 1,053,510 $ 942,003 Net income (loss) $ ( 48,084 ) $ ( 44,154 ) $ ( 60,494 ) $ ( 133,321 )

Cash, Cash Equivalents and Re_2

Cash, Cash Equivalents and Restricted Cash (Tables)	9 Months Ended
	Sep. 30, 2022
Cash and Cash Equivalents [Abstract]
Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statements of Cash Flows: As of As of (In thousands) September 30, 2022 December 31, 2021 Cash and cash equivalents $ 111,099 $ 56,603 Restricted cash — 215 Cash, cash equivalents and restricted cash $ 111,099 $ 56,818

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Disaggregate of Revenue by Reportable Segment and Revenue Category	The following tables disaggregate revenue by reportable segment and revenue category. Prior year amounts presented below have been reclassified to conform to the current period revenue category presentation: Three Months Ended September 30, 2022 September 30, 2021 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Subscriber Solutions $ 125,338 $ 8,337 $ 133,675 $ 42,704 $ 4,163 $ 46,867 Access & Aggregation Solutions 76,591 11,598 88,189 78,063 13,151 91,214 Optical Networking Solutions 103,011 15,834 118,845 — — — Total $ 304,940 $ 35,769 $ 340,709 $ 120,767 $ 17,314 $ 138,081 Nine Months Ended September 30, 2022 September 30, 2021 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Subscriber Solutions $ 252,899 $ 17,248 $ 270,147 $ 140,257 $ 12,232 $ 152,489 Access & Aggregation Solutions 243,396 34,877 278,273 219,768 36,589 256,357 Optical Networking Solutions 103,011 15,834 118,845 — — — Total $ 599,306 $ 67,959 $ 667,265 $ 360,025 $ 48,821 $ 408,846 The table below presents revenue information by category. Prior year amounts presented below have been reclassified to conform to the current period revenue category presentation: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Subscriber Solutions $ 133,675 $ 46,867 $ 270,147 $ 152,489 Access & Aggregation Solutions 88,189 91,214 278,273 256,357 Optical Networking Solutions 118,845 — 118,845 — Total $ 340,709 $ 138,081 $ 667,265 $ 408,846
Information about Receivables, Contract Assets, and Unearned Revenue from Contracts with Customers	The following table provides information about receivables, contract assets and unearned revenue from contracts with customers: As of As of (In thousands) September 30, 2022 December 31, 2021 Accounts receivable, net $ 302,401 $ 158,742 Contract assets (1) $ 1,790 $ 464 Unearned revenue $ 40,993 $ 17,737 Non-current unearned revenue $ 18,269 $ 9,271

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Summary of Supplemental Balance Sheet Information Related to Deferred Tax Assets (Liabilities)	Supplemental balance sheet information related to deferred tax assets (liabilities) is as follows: As of September 30, 2022 (In thousands) Deferred Tax Assets (Liabilities) Valuation Allowance Deferred Tax Liabilities, net Domestic $ 68,723 $ ( 64,054 ) $ 4,669 International ( 39,493 ) ( 2,060 ) ( 41,553 ) Total $ 29,230 $ ( 66,114 ) $ ( 36,884 ) As of December 31, 2021 (In thousands) Deferred Tax Assets Valuation Allowance Deferred Tax Assets, net Domestic $ 48,265 $ ( 48,265 ) $ — International 11,378 ( 2,299 ) 9,079 Total $ 59,643 $ ( 50,564 ) $ 9,079

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Expense Related to Stock Options, RSUs and Restricted Stock	The following table summarizes the RSUs and restricted stock outstanding as of December 31, 2021 and September 30, 2022 and the changes that occurred during the nine months ended September 30, 2022: Number of Weighted Avg. Grant Date Fair Value Unvested RSUs and restricted stock outstanding, December 31, 2021 1,930 $ 14.11 RSUs and restricted stock granted 545 $ 19.96 RSUs and restricted stock vested ( 20 ) $ 13.67 RSUs and restricted stock forfeited ( 46 ) $ 14.18 Unvested RSUs and restricted stock outstanding, September 30, 2022 2,409 $ 17.36
Summary of Stock Options Outstanding	The following table summarizes ADTRAN Holdings, Inc. stock options outstanding as of December 31, 2021 and September 30, 2022 and the changes that occurred during the nine months ended September 30, 2022: Number of Weighted Avg. Weighted Avg. Aggregate Stock options outstanding, December 31, 2021 1,721 $ 19.37 2.4 $ 6,669 ADVA stock options replaced by ADTRAN Holdings stock options (1) 1,980 $ 11.16 Stock options exercised ( 439 ) $ 16.16 Stock options forfeited ( 12 ) $ 11.08 Stock options expired ( 70 ) $ 26.38 Stock options outstanding, September 30, 2022 3,180 $ 14.58 3.5 $ 17,839 Stock options exercisable, September 30, 2022 1,627 $ 16.85 2.0 $ 6,375 (1) Each ADVA stock option surrendered was exchanged for 0.8244 ADTRAN Holdings stock options.
ADVA Optical Networking SE [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Stock Options Outstanding	The following table summarizes ADVA Optical Networking SE stock options outstanding as of July 15, 2022 (the Business Combination closing date) and September 30, 2022 and the changes that occurred between July 15, 2022 and September 30, 2022: Number of Weighted Avg. Weighted Avg. Aggregate Stock options outstanding, July 15, 2022 2,745 $ 9.09 4.6 $ 27,205 Stock options exercised ( 56 ) $ 6.79 ADVA stock options replaced by ADTRAN Holdings stock options (1) ( 2,403 ) $ 9.25 Stock options forfeited ( 4 ) $ 7.91 Stock options outstanding, September 30, 2022 282 $ 8.45 3.9 $ 2,976 Stock options exercisable, September 30, 2022 32 $ 7.72 1.2 $ 363 (1) Each ADVA stock option surrendered was exchanged for 0.8244 ADTRAN Holdings stock options.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Debt Securities and Other Investments, Included on Condensed Consolidated Balance Sheet and Recorded at Fair Value	Debt Securities and Other Investments The following debt securities and other investments were included on the Condensed Consolidated Balance Sheets and recorded at fair value: As of September 30, 2022 Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 9,358 $ — $ ( 374 ) $ 8,984 Municipal fixed-rate bonds 1,411 — ( 54 ) 1,357 Asset-backed bonds 2,988 — ( 77 ) 2,911 Mortgage/Agency-backed bonds 4,720 — ( 280 ) 4,440 U.S. government bonds 11,231 — ( 642 ) 10,589 Foreign government bonds 409 — ( 27 ) 382 Available-for-sale debt securities held at fair value $ 30,117 $ — $ ( 1,454 ) $ 28,663 As of December 31, 2021 Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 10,776 $ 6 $ ( 35 ) $ 10,747 Municipal fixed-rate bonds 1,553 2 ( 4 ) 1,551 Asset-backed bonds 322 3 ( 3 ) 322 Mortgage/Agency-backed bonds 4,754 15 ( 33 ) 4,736 U.S. government bonds 12,251 12 ( 92 ) 12,171 Foreign government bonds 543 — ( 4 ) 539 Available-for-sale debt securities held at fair value $ 30,199 $ 38 $ ( 171 ) $ 30,066
Contractual Maturities of Debt Securities and Other Investments	The contractual maturities related to debt securities and other investments were as follows: As of September 30, 2022 (In thousands) Corporate Municipal Asset- Mortgage/ U.S. government Foreign government bonds Less than one year $ 96 $ 525 $ — $ 182 $ — $ — One to two years 5,371 722 95 464 7,421 275 Two to three years 3,517 110 715 1,321 2,889 107 Three to five years — — 1,306 166 279 — Five to ten years — — 382 810 — — More than ten years — — 413 1,497 — — Total $ 8,984 $ 1,357 $ 2,911 $ 4,440 $ 10,589 $ 382
Gross Realized Gains and Losses on Sale of Debt Securities	The following table presents the gross realized gains and losses related to its debt securities: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Gross realized gain on debt securities $ 1 $ 22 $ 14 $ 206 Gross realized loss on debt securities ( 116 ) ( 17 ) ( 242 ) ( 53 ) Total (loss) gain recognized, net $ ( 115 ) $ 5 $ ( 228 ) $ 153
Realized and Unrealized Gains and Losses related to Marketable Equity Securities	Realized and unrealized gains and losses related to marketable equity securities were as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Realized (loss) gain on equity securities sold $ ( 1,358 ) $ — $ ( 1,675 ) $ ( 55 ) Unrealized (loss) gain on equity securities held ( 1,217 ) ( 68 ) ( 8,849 ) 2,844 Total (loss) gain recognized, net $ ( 2,575 ) $ ( 68 ) $ ( 10,524 ) $ 2,789
Cash Equivalents and Investments held at Fair Value	The Company’s cash equivalents and investments held at fair value are categorized into this hierarchy as follows: Fair Value Measurements as of September 30, 2022 Using (In thousands) Fair Value Quoted Prices Significant Significant Unobservable Inputs Cash equivalents Money market funds $ 698 $ 698 $ — $ — Available-for-sale debt securities Corporate bonds 8,984 — 8,984 — Municipal fixed-rate bonds 1,357 — 1,357 — Asset-backed bonds 2,911 — 2,911 — Mortgage/Agency-backed bonds 4,440 — 4,440 — U.S. government bonds 10,589 10,589 — — Foreign government securities 382 — 382 — Marketable equity securities Marketable equity securities – various industries 760 760 — — Deferred compensation plan assets 21,511 21,511 — — Total $ 51,632 $ 33,558 $ 18,074 $ — Fair Value Measurements as of December 31, 2021 Using (In thousands) Fair Value Quoted Prices Significant Significant Unobservable Inputs Cash equivalents Money market funds $ 652 $ 652 $ — $ — Available-for-sale debt securities Corporate bonds 10,747 — 10,747 — Municipal fixed-rate bonds 1,551 — 1,551 — Asset-backed bonds 322 — 322 — Mortgage/Agency-backed bonds 4,736 — 4,736 — U.S. government bonds 12,171 12,171 — — Foreign government bonds 539 — 539 — Marketable equity securities Marketable equity securities – various industries 12,606 12,606 — — Deferred compensation plan assets 26,935 26,935 — — Total $ 70,259 $ 52,364 $ 17,895 $ —

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2022
Inventory Disclosure [Abstract]
Components of Inventory	Inventory consisted of the following: As of As of (In thousands) September 30, 2022 December 31, 2021 Raw materials $ 177,554 $ 74,709 Work in process 10,625 2,143 Finished goods 227,984 63,039 Total inventory, net $ 416,163 $ 139,891

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2022
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment consisted of the following: As of As of (In thousands) September 30, 2022 December 31, 2021 Engineering and other equipment $ 162,445 $ 134,771 Building 80,807 68,157 Computer hardware and software 79,990 72,274 Building and land improvements 40,132 35,578 Furniture and fixtures 20,891 19,917 Land 5,298 4,575 Other assets 4,835 — Total property, plant and equipment 394,398 335,272 Less: accumulated depreciation ( 289,821 ) ( 279,506 ) Total property, plant and equipment, net $ 104,577 $ 55,766

Goodwill (Tables)

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2022
Goodwill Disclosure [Abstract]
Summary of Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the nine months ended September 30, 2022 are as follows: (In thousands) Network Solutions Services & Support Total As of December 31, 2021 $ 6,568 $ 400 $ 6,968 Goodwill from Business Combination with ADVA 270,568 88,589 359,157 Foreign currency translation adjustments ( 6,220 ) ( 2,036 ) ( 8,256 ) As of September 30, 2022 $ 270,916 $ 86,953 $ 357,869

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2022
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Summary of Intangible Assets	Intangible assets consisted of the following: As of September 30, 2022 As of December 31, 2021 (In thousands) Weighted Average Useful Life Gross Carrying Amount Accumulated Amortization Net Book Value Gross Carrying Amount Accumulated Amortization Net Book Value Customer relationships 10.9 $ 52,139 $ ( 11,207 ) $ 40,932 $ 20,796 $ ( 9,906 ) $ 10,890 Backlog 1.4 50,966 ( 9,325 ) 41,641 — — — Developed technology 8.5 294,983 ( 11,565 ) 283,418 8,200 ( 3,683 ) 4,517 Licensed technology 9.0 5,900 ( 2,977 ) 2,923 5,900 ( 2,486 ) 3,414 Licensing agreements 8.5 560 ( 280 ) 280 560 ( 225 ) 335 Patents 7.3 500 ( 414 ) 86 500 ( 363 ) 137 Trade names 2.8 26,575 ( 2,280 ) 24,295 210 ( 210 ) — Total $ 431,623 $ ( 38,048 ) $ 393,575 $ 36,166 $ ( 16,873 ) $ 19,293
Estimated Future Amortization Expense Related to Intangible Assets	Estimated future amortization expense of intangible assets was as follows: As of (In thousands) September 30, 2022 2022 $ 23,691 2023 75,677 2024 53,021 2025 42,623 2026 39,505 Thereafter 159,058 Total $ 393,575

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2022
Leases [Abstract]
Schedule of Supplemental Balance Sheet Information Related to Operating Leases	Supplemental balance sheet information related to operating leases is as follows: (In thousands) Classification September 30, 2022 December 31, 2021 Assets Operating lease asset Other assets $ 28,081 $ 4,922 Total lease asset $ 28,081 $ 4,922 Liabilities Current operating lease liability Accrued expenses $ 6,604 $ 1,730 Non-current operating lease liability Non-current lease obligations 21,490 3,269 Total lease liability $ 28,094 $ 4,999
Components of Lease Expense included in Consolidated Statements of Loss	The components of lease expense included in the Condensed Consolidated Statements of Loss were as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Selling, general and administrative expenses $ 1,444 $ 196 $ 1,704 $ 645 Research and development expenses 228 261 719 815 Cost of sales 20 14 59 38 Total operating lease expense $ 1,692 $ 471 $ 2,482 $ 1,498
Schedule of Maturity of Operating Lease Liabilities	As of September 30, 2022 and December 31, 2021, operating lease liabilities included on the Condensed Consolidated Balance Sheets by future maturity were as follows: (In thousands) September 30, 2022 December 31, 2021 2022 $ 2,209 $ 1,767 2023 8,421 1,419 2024 7,098 1,188 2025 5,838 710 2026 3,354 — Thereafter 5,107 — Total lease payments 32,027 5,084 Less: Interest ( 3,933 ) ( 85 ) Present value of lease liabilities $ 28,094 $ 4,999
Schedule of Weighted Average Remaining Lease Terms and Weighted Average Discount Rates	The following table provides information about our weighted average lease terms and weighted average discount rates: As of September 30, 2022 Weighted average remaining lease term (in years) Operating leases with USD functional currency 1.6 Operating leases with Euro functional currency 4.5 Weighted average discount rate Operating leases with USD functional currency 3.93 % Operating leases with Euro functional currency 4.05 %
Net Investment in Sales-Type Leases	We are the lessor in sales-type lease arrangements for network equipment, which consisted of the following: As of As of (In thousands) September 30, 2022 December 31, 2021 Current minimum lease payments receivable (1) $ 11 $ 92 Non-current minimum lease payments receivable (2) — 4 Total minimum lease payments receivable 11 96 Less: Current unearned revenue (1) 5 70 Less: Non-current unearned revenue (2) — 1 Net investment in sales-type leases $ 6 $ 25 (1) Included in other receivables on the Condensed Consolidated Balance Sheets. (2) Included in other assets on the Condensed Consolidated Balance Sheets.

Revolving Credit Agreement (Tab

Revolving Credit Agreement (Tables)	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Carrying Amount of Revolving Agreement	The carrying amounts of the Company's revolving credit agreements in its Condensed Consolidated Balance Sheets were as follows: As of As of (In thousands) September 30, 2022 December 31, 2021 Wells Fargo credit agreement $ 60,000 $ — Nord/LB revolving line of credit 14,702 — Syndicated credit agreement working capital line of credit 9,801 — Wells Fargo revolving credit agreement — — Cadence revolving credit agreement — — Total revolving credit agreements $ 84,503 $ —

Notes Payable (Tables)

Notes Payable (Tables)	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Carrying Amounts of Notes Payables	The carrying amounts of the Company's notes payable in its Condensed Consolidated Balance Sheets were as follows: Fair Value as of Carrying Value as of Carrying Value as of (In thousands) September 30, 2022 September 30, 2022 December 31, 2021 Syndicated credit agreement note payable $ 29,611 $ 29,782 $ — Deutsche Bank term loan — — — Total Notes Payable $ 29,611 $ 29,782 $ —

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2022
Retirement Benefits [Abstract]
Schedule of the Components of Net Periodic Pension Cost	The following table summarizes the components of net periodic pension cost related to a defined benefit pension plan covering employees in certain foreign countries: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Service cost $ 478 $ 307 $ 981 $ 931 Interest cost 204 84 638 257 Expected return on plan assets ( 465 ) ( 460 ) ( 1,384 ) ( 1,396 ) Amortization of actuarial losses 81 272 254 825 Net periodic pension cost $ 298 $ 203 $ 489 $ 617

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2022
Equity [Abstract]
Changes in Accumulated Other Comprehensive Loss, Net of Tax, by Component	The following tables present the changes in accumulated other comprehensive loss, net of tax, by component: Three Months Ended September 30, 2022 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance as of June 30, 2022 $ ( 1,476 ) $ ( 5,713 ) $ ( 9,892 ) $ 385 $ ( 16,696 ) Other comprehensive loss before ( 254 ) — ( 23,172 ) — ( 23,426 ) Amounts reclassified from accumulated other ( 142 ) ( 118 ) — — ( 260 ) Net current period other comprehensive (loss) income ( 396 ) ( 118 ) ( 23,172 ) — ( 23,686 ) Less: Comprehensive Loss attributable to non-controlling interest, net of tax — — ( 94 ) — ( 94 ) Balance as of September 30, 2022 $ ( 1,872 ) $ ( 5,831 ) $ ( 32,970 ) $ 385 $ ( 40,288 ) Three Months Ended September 30, 2021 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance as of June 30, 2021 $ ( 255 ) $ ( 9,310 ) $ ( 3,960 ) $ 385 $ ( 13,140 ) Other comprehensive loss before ( 29 ) — ( 1,389 ) — ( 1,418 ) Amounts reclassified from accumulated other ( 32 ) 124 — — 92 Net current period other comprehensive (loss) income ( 61 ) 124 ( 1,389 ) — ( 1,326 ) Balance as of September 30, 2021 $ ( 316 ) $ ( 9,186 ) $ ( 5,349 ) $ 385 $ ( 14,466 ) Nine Months Ended September 30, 2022 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total As of December 31, 2021 $ ( 552 ) $ ( 5,613 ) $ ( 6,134 ) $ 385 $ ( 11,914 ) Other comprehensive loss before ( 1,818 ) — ( 26,930 ) — ( 28,748 ) Amounts reclassified from accumulated other 498 ( 218 ) — — 280 Net current period other comprehensive loss ( 1,320 ) ( 218 ) ( 26,930 ) — ( 28,468 ) Less: Comprehensive Loss attributable to non-controlling interest, net of tax — — ( 94 ) — ( 94 ) As of September 30, 2022 $ ( 1,872 ) $ ( 5,831 ) $ ( 32,970 ) $ 385 $ ( 40,288 ) Nine Months Ended September 30, 2021 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total As of December 31, 2020 $ 32 $ ( 9,621 ) $ ( 2,435 ) $ 385 $ ( 11,639 ) Other comprehensive loss before ( 358 ) — ( 2,914 ) — ( 3,272 ) Amounts reclassified from accumulated other 10 435 — — 445 Net current period other comprehensive (loss) income ( 348 ) 435 ( 2,914 ) — ( 2,827 ) As of September 30, 2021 $ ( 316 ) $ ( 9,186 ) $ ( 5,349 ) $ 385 $ ( 14,466 )
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)	The following tables present the details of reclassifications out of accumulated other comprehensive loss: Three Months Ended September 30, 2022 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized loss on sales of securities $ 187 Net investment (loss) gain Defined benefit plan adjustments – actuarial loss 171 (1) Total reclassifications for the period, before tax 358 Tax benefit ( 98 ) Total reclassifications for the period, net of tax $ 260 (1) A part of the computation of net periodic pension cost, which is included in other income, net in the Condensed Consolidated Statements of Loss. Three Months Ended September 30, 2021 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized loss on sales of securities $ 42 Net investment (loss) gain Defined benefit plan adjustments – actuarial gain ( 180 ) (1) Total reclassifications for the period, before tax ( 138 ) Tax expense 46 Total reclassifications for the period, net of tax $ ( 92 ) (1) A part of the computation of net periodic pension cost, which is included in other income, net in the Condensed Consolidated Statements of Loss. Nine Months Ended September 30, 2022 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized gain on sales of securities $ ( 655 ) Net investment (loss) gain Defined benefit plan adjustments – actuarial loss 316 (1) Total reclassifications for the period, before tax ( 339 ) Tax expense 59 Total reclassifications for the period, net of tax $ ( 280 ) (1) A part of the computation of net periodic pension cost, which is included in other income, net in the Condensed Consolidated Statements of Loss. Nine Months Ended September 30, 2021 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized gain on sales of securities $ ( 13 ) Net investment (loss) gain Defined benefit plan adjustments – actuarial gain ( 630 ) (1) Total reclassifications for the period, before tax ( 643 ) Tax expense 198 Total reclassifications for the period, net of tax $ ( 445 ) (1) A part of the computation of net periodic pension cost, which is included in other income, net in the Condensed Consolidated Statements of Loss.
Tax Effects Related to the Change in Each Component of Other Comprehensive Loss	The following tables present the tax effects related to the change in each component of other comprehensive loss: Three Months Ended Three Months Ended September 30, 2022 September 30, 2021 (In thousands) Before-Tax Tax Net-of-Tax Before-Tax Tax Net-of-Tax Unrealized loss on available-for-sale $ ( 334 ) $ 80 $ ( 254 ) $ ( 38 ) $ 9 $ ( 29 ) Reclassification adjustment for amounts related to ( 187 ) 45 ( 142 ) ( 42 ) 10 ( 32 ) Reclassification adjustment for amounts related to ( 171 ) 53 ( 118 ) 180 ( 56 ) 124 Foreign currency translation adjustments ( 23,172 ) — ( 23,172 ) ( 1,389 ) — ( 1,389 ) Total Other Comprehensive Loss $ ( 23,864 ) $ 178 $ ( 23,686 ) $ ( 1,289 ) $ ( 37 ) $ ( 1,326 ) Nine Months Ended Nine Months Ended September 30, 2022 September 30, 2021 (In thousands) Before-Tax Tax Net-of-Tax Before-Tax Tax Net-of-Tax Unrealized loss on available-for-sale $ ( 2,392 ) $ 574 $ ( 1,818 ) $ ( 471 ) $ 113 $ ( 358 ) Reclassification adjustment for amounts related to 655 ( 157 ) 498 13 ( 3 ) 10 Reclassification adjustment for amounts related to ( 316 ) 98 ( 218 ) 630 ( 195 ) 435 Foreign currency translation adjustments ( 26,930 ) — ( 26,930 ) ( 2,914 ) — ( 2,914 ) Total Other Comprehensive Loss $ ( 28,983 ) $ 515 $ ( 28,468 ) $ ( 2,742 ) $ ( 85 ) $ ( 2,827 )

Loss Per Share (Tables)

Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2022
Earnings Per Share [Abstract]
Summary of Calculation of Basic and Diluted Loss Per Share	The calculation of basic and diluted loss per share is as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands, except per share amounts) 2022 2021 2022 2021 Numerator Net loss attributable to ADTRAN Holdings, Inc. $ ( 41,934 ) $ ( 10,427 ) $ ( 40,918 ) $ ( 4,445 ) Denominator Weighted average number of shares – basic 73,036 48,609 57,175 48,470 Effect of dilutive securities Stock options — — — — PSUs, RSUs and restricted stock — — — — Weighted average number of shares – diluted 73,036 48,609 57,175 48,470 Loss per share attributable to ADTRAN Holdings, Inc. – basic $ ( 0.57 ) $ ( 0.21 ) $ ( 0.72 ) $ ( 0.09 ) Loss per share attributable to ADTRAN Holdings, Inc. – diluted $ ( 0.57 ) $ ( 0.21 ) $ ( 0.72 ) $ ( 0.09 )

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2022
Segment Reporting [Abstract]
Revenue and Gross Profit of Reportable Segments	The following tables present information about the revenue and gross profit of its reportable segments: Three Months Ended September 30, 2022 September 30, 2021 (In thousands) Revenue Gross Profit Revenue Gross Profit Network Solutions $ 304,940 $ 82,334 $ 120,767 $ 39,738 Services & Support 35,769 20,693 17,314 7,935 Total $ 340,709 $ 103,027 $ 138,081 $ 47,673 Nine Months Ended September 30, 2022 September 30, 2021 (In thousands) Revenue Gross Profit Revenue Gross Profit Network Solutions $ 599,306 $ 186,126 $ 360,025 $ 143,981 Services & Support 67,959 33,723 48,821 19,961 Total $ 667,265 $ 219,849 $ 408,846 $ 163,942
Disaggregate of Revenue by Reportable Segment and Revenue Category	The following tables disaggregate revenue by reportable segment and revenue category. Prior year amounts presented below have been reclassified to conform to the current period revenue category presentation: Three Months Ended September 30, 2022 September 30, 2021 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Subscriber Solutions $ 125,338 $ 8,337 $ 133,675 $ 42,704 $ 4,163 $ 46,867 Access & Aggregation Solutions 76,591 11,598 88,189 78,063 13,151 91,214 Optical Networking Solutions 103,011 15,834 118,845 — — — Total $ 304,940 $ 35,769 $ 340,709 $ 120,767 $ 17,314 $ 138,081 Nine Months Ended September 30, 2022 September 30, 2021 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Subscriber Solutions $ 252,899 $ 17,248 $ 270,147 $ 140,257 $ 12,232 $ 152,489 Access & Aggregation Solutions 243,396 34,877 278,273 219,768 36,589 256,357 Optical Networking Solutions 103,011 15,834 118,845 — — — Total $ 599,306 $ 67,959 $ 667,265 $ 360,025 $ 48,821 $ 408,846 The table below presents revenue information by category. Prior year amounts presented below have been reclassified to conform to the current period revenue category presentation: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Subscriber Solutions $ 133,675 $ 46,867 $ 270,147 $ 152,489 Access & Aggregation Solutions 88,189 91,214 278,273 256,357 Optical Networking Solutions 118,845 — 118,845 — Total $ 340,709 $ 138,081 $ 667,265 $ 408,846
Revenue Information by Geographic Area	The following table presents revenue information by geographic area: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 United States $ 169,669 $ 91,868 $ 374,470 $ 273,009 United Kingdom 64,234 12,504 123,477 34,006 Germany 46,569 17,782 71,945 50,737 Other international 60,237 15,927 97,373 51,094 Total $ 340,709 $ 138,081 $ 667,265 $ 408,846

Liability for Warranty Returns

Liability for Warranty Returns (Tables)	9 Months Ended
	Sep. 30, 2022
Product Warranties Disclosures [Abstract]
Summary of Warranty Expense and Write-off Activity	The warranty expense and write-off activity for the three and nine months ended September 30, 2022 and 2021 are summarized as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2022 2021 2022 2021 Balance at beginning of period $ 4,842 $ 5,997 $ 5,403 $ 7,146 Plus: ADVA acquisition 3,756 — 3,756 — Plus: Amounts charged to cost and expenses 616 472 1,727 253 Less: Deductions ( 613 ) ( 822 ) ( 2,285 ) ( 1,752 ) Balance at end of period $ 8,601 $ 5,647 $ 8,601 $ 5,647

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - $ / shares			9 Months Ended
	Jul. 15, 2022	Aug. 30, 2021	Sep. 30, 2022	Oct. 18, 2022	Dec. 31, 2021
Summary Of Significant Accounting Policy [Line Items]
Common stock, par value		$ 0.01	$ 0.01		$ 0.01
Common stock, shares outstanding			77,619,000		49,063,000
Issuance of shares of common stock	28,000,000	27,994,595
Subsequent Event [Member] | DPLTA [Member]
Summary Of Significant Accounting Policy [Line Items]
Percentage of required voting interest				75%
Acorn HoldCo, Inc., [Member]
Summary Of Significant Accounting Policy [Line Items]
Business combination date of agreement		Aug. 30, 2021
Number of shares issuable for each share of acquired entity	100,000
Common stock, par value		$ 0.01
Common stock, shares outstanding	34,000,000		33,957,538
Percentage of outstanding bearer shares	65.43%		65.35%
Acorn HoldCo, Inc., [Member] | ADVA Optical Networking SE [Member] | Common Stock [Member]
Summary Of Significant Accounting Policy [Line Items]
Number of shares issuable for each share of acquired entity		0.8244

Business Combination - Addition

Business Combination - Additional Information (Details) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Jul. 15, 2022 USD ($) $ / shares shares	Aug. 30, 2021 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) $ / shares shares	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) $ / shares shares	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) $ / shares shares	Aug. 30, 2021 € / shares shares
Business Acquisition [Line Items]
Common stock, par value | $ / shares		$ 0.01	$ 0.01		$ 0.01		$ 0.01
Exchange offer settled date	Jul. 15, 2022
Common stock, shares outstanding | shares			77,619,000		77,619,000		49,063,000
Common stock, reserved for future issuance | shares	28,000,000	27,994,595						27,994,595
Goodwill			$ 357,869		$ 357,869		$ 6,968
Net revenue			340,709	$ 138,081	667,265	$ 408,846
Net loss attributable to ADTRAN Holdings, Inc.			(41,934)	(10,427)	(40,918)	(4,445)
Net loss attributable to non-controlling interest			(2,925)		(2,925)
Network Solutions [Member]
Business Acquisition [Line Items]
Goodwill			270,916		270,916		6,568
Net revenue			304,940	120,767	599,306	360,025
Services & Support [Member]
Business Acquisition [Line Items]
Goodwill			86,953		86,953		$ 400
Net revenue			35,769	17,314	67,959	48,821
Common Stock [Member]
Business Acquisition [Line Items]
Percentage of common stock exchanged		64%
ADVA Optical Networking SE [Member]
Business Acquisition [Line Items]
Business combination date of agreement		Aug. 30, 2021
Common stock, shares outstanding | shares		33,957,538						33,957,538
Percentage of outstanding bearer shares		65.43%
Fair value of stock options assumed		$ 12,800
Goodwill	$ 359,157		359,200		359,200
Accounts receivable	114,659
Other receivables	1,457
Unpaid principal balance of account receivable	118,500
Unpaid principal balance of other receivable	1,500
Fair value of noncontrolling interest	316,415
Net revenue	163,800
Net loss attributable to ADTRAN Holdings, Inc.	$ 8,400
Net loss attributable to non-controlling interest			(2,900)		(2,900)
Shares held by noncontrolling interest | shares		17,941,496						17,941,496
Closing share price | (per share)	$ 20.20	$ 17.64						€ 17.58
Currency conversion rate	1.00318
ADVA Optical Networking SE [Member] | Selling, General and Administrative Expense [Member]
Business Acquisition [Line Items]
Transaction costs incurred					25,200
Transaction costs related to the business combination			$ 10,600	$ 5,100	13,300	$ 6,400
Estimated additional transaction costs to be incurred					$ 1,100
ADVA Optical Networking SE [Member] | Network Solutions [Member]
Business Acquisition [Line Items]
Goodwill	$ 270,600
ADVA Optical Networking SE [Member] | Services & Support [Member]
Business Acquisition [Line Items]
Goodwill	$ 88,600
ADVA Optical Networking SE [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Number of shares issuable for each share of acquired entity | shares		0.8244
Percentage of common stock exchanged		36%

Business Combination - Summary

Business Combination - Summary of Purchase Price for Business Combination (Details) - ADVA Optical Networking SE [Member] $ / shares in Units, $ in Thousands	Jul. 15, 2022 USD ($) $ / shares shares	Aug. 30, 2021 $ / shares	Aug. 30, 2021 € / shares
Business Acquisition [Line Items]
ADVA shares exchanged | shares	33,957,538
Exchange ratio	0.8244
ADTRAN Holdings, Inc. shares issued | shares	27,994,595
ADTRAN Holdings, Inc. share price on July 15, 2022 | (per share)	$ 20.20	$ 17.64	€ 17.58
Purchase price paid for ADVA shares	$ 565,491
Equity compensation	12,769
Total purchase price	$ 578,260

Business Combination - Summar_2

Business Combination - Summary of Purchase Price Allocation of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Jul. 15, 2022	Dec. 31, 2021
Net Assets:
Goodwill	$ 357,869		$ 6,968
ADVA Optical Networking SE [Member]
Business Acquisition [Line Items]
Total purchase price		$ 578,260
Noncontrolling interest		316,415
Net Assets:
Cash and cash equivalents		44,003
Accounts receivable		114,659
Other receivables		1,457
Inventory		200,532
Prepaid expenses and other current assets		29,474
Property plant and equipment		52,796
Deferred tax assets		1,599
Intangibles		405,385
Other non-current assets		30,588
Accounts payable		(98,587)
Current unearned revenue		(26,047)
Accrued expenses and other liabilities		(59,600)
Current portion of notes payable		(25,254)
Income tax payable		(1,400)
Non-current unearned revenue		(11,498)
Pension liability		(6,820)
Other non-current liabilities		(6,094)
Non-current portion of revolving credit agreements and notes payable		(15,250)
Non-current lease obligations		(20,046)
Deferred tax liabilities		(74,379)
Total net assets acquired		535,518
Goodwill	$ 359,200	$ 359,157

Business Combination - Summar_3

Business Combination - Summary of Fair Value of Intangible Assets Acquired (Details) - ADVA Optical Networking SE [Member] $ in Thousands	Jul. 15, 2022 USD ($)
Business Acquisition [Line Items]
Fair value	$ 405,385
Cost of Revenue [Member] | Network Solutions [Member] | Developed Technology [Member]
Business Acquisition [Line Items]
Estimated-average useful life (in years)	8 years 6 months	[1]
Fair value	$ 293,530
Cost of Revenue [Member] | Network Solutions and Services & Support [Member] | Backlog [Member]
Business Acquisition [Line Items]
Estimated-average useful life (in years)	1 year 4 months 24 days	[1]
Fair value	$ 52,165
Selling, General and Administrative Expense [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Estimated-average useful life (in years)	10 years 6 months	[1]
Fair value	$ 32,704
Selling, General and Administrative Expense [Member] | Trade Name [Member]
Business Acquisition [Line Items]
Estimated-average useful life (in years)	2 years 9 months 18 days	[1]
Fair value	$ 26,986
[1] Determination of the weighted average period of the individual categories of intangible assets was based on the nature of the applicable intangible asset and the expected future cash flows to be derived from the intangible asset. Amortization of intangible assets with definite lives is recognized over the period of time the assets are expected to contribute to future cash flows.

Business Combination - Summar_4

Business Combination - Summary of Unaudited Pro Forma Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Business Combinations [Abstract]
Revenue	$ 368,192	$ 317,067	$ 1,053,510	$ 942,003
Net income (loss)	$ (48,084)	$ (44,154)	$ (60,494)	$ (133,321)

Cash, Cash Equivalents and Re_3

Cash, Cash Equivalents and Restricted Cash - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 111,099	$ 56,603
Restricted cash		215
Cash, cash equivalents and restricted cash	$ 111,099	$ 56,818

Revenue - Additional Informatio

Revenue - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) Category	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Revenue [Line Items]
Number of categories | Category			3
Increase in accounts receivable			$ 34,535,000	$ 26,346,000
Accounts receivable, net	$ 302,401,000		302,401,000		$ 158,742,000
Accounts receivable, allowance for doubtful accounts	218,000		218,000		0
Recognized revenue	2,800,000	$ 2,000,000	12,300,000	$ 9,800,000
Outstanding unearned revenue						$ 14,100,000
Contract assets, allowance for credit losses	0		0		0
Purchase Agreement [Member] | Factor [Member]
Revenue [Line Items]
Accounts receivable sold	16,100,000		16,100,000
Accounts receivable, allowance for doubtful accounts	100,000		100,000
Interest expense [Member] | Purchase Agreement [Member] | Factor [Member]
Revenue [Line Items]
Cost of receivables	300,000		300,000
Other assets [Member] | Purchase Agreement [Member] | Factor [Member]
Revenue [Line Items]
Accounts receivable gross	1,300,000		1,300,000
Existing sale of receivables [Member] | Purchase Agreement [Member] | Factor [Member]
Revenue [Line Items]
Accounts receivable, net	31,100,000		31,100,000
Contractual Maintenance Agreements, Contractual SaaS and Subscription Services and Hardware Contracts [Member]
Revenue [Line Items]
Remaining performance obligations	$ 276,500,000		$ 276,500,000		$ 101,100,000

Revenue - Disaggregate of Reven

Revenue - Disaggregate of Revenue by Reportable Segment and Revenue Category (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation Of Revenue [Line Items]
Revenue	$ 340,709	$ 138,081	$ 667,265	$ 408,846
Subscriber Solutions
Disaggregation Of Revenue [Line Items]
Revenue	133,675	46,867	270,147	152,489
Access & Aggregation Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	88,189	91,214	278,273	256,357
Optical Networking Solutions
Disaggregation Of Revenue [Line Items]
Revenue	118,845		118,845
Network Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	304,940	120,767	599,306	360,025
Network Solutions [Member] | Subscriber Solutions
Disaggregation Of Revenue [Line Items]
Revenue	125,338	42,704	252,899	140,257
Network Solutions [Member] | Access & Aggregation Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	76,591	78,063	243,396	219,768
Network Solutions [Member] | Optical Networking Solutions
Disaggregation Of Revenue [Line Items]
Revenue	103,011		103,011
Services & Support [Member]
Disaggregation Of Revenue [Line Items]
Revenue	35,769	17,314	67,959	48,821
Services & Support [Member] | Subscriber Solutions
Disaggregation Of Revenue [Line Items]
Revenue	8,337	4,163	17,248	12,232
Services & Support [Member] | Access & Aggregation Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	11,598	$ 13,151	34,877	$ 36,589
Services & Support [Member] | Optical Networking Solutions
Disaggregation Of Revenue [Line Items]
Revenue	$ 15,834		$ 15,834

Revenue - Additional Informat_2

Revenue - Additional Information (Detail1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-10-01	Sep. 30, 2022
Revenue [Line Items]
Remaining performance obligations, percentage	82%
Remaining performance obligations, period	12 months

Revenue - Information about Rec

Revenue - Information about Receivables, Contract Assets, and Unearned Revenue from Contracts with Customers (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Accounts receivable, net	$ 302,401	$ 158,742
Contract assets	1,790	464
Unearned revenue	40,993	17,737
Non-current unearned revenue	$ 18,269	$ 9,271

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Income Tax Disclosure [Line Items]
Effective tax rate expense (benefit)	8.80%	14.10%	9.40%	354.50%
Deferred tax assets	$ 29,200		$ 29,200		$ 9,079
Valuation allowance established against deferred tax assets	66,114		66,114		50,564
Deferred tax liabilities	36,884		36,884
Domestic [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets	4,669		4,669
Valuation allowance established against deferred tax assets	64,054		64,054		48,265
Change in deferred tax asset valuation allowance			15,800
International [Member]
Income Tax Disclosure [Line Items]
Deferred tax assets					9,079
Valuation allowance established against deferred tax assets	2,060		2,060		$ 2,299
Deferred tax liabilities	$ 41,553		41,553
Change in deferred tax asset valuation allowance			$ 200

Income Taxes - Summary of Suppl

Income Taxes - Summary of Supplemental Balance Sheet Information Related to Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets	$ 29,230	$ 59,643
Valuation Allowance	(66,114)	(50,564)
Deferred Tax Assets, net	29,200	9,079
Deferred Tax Liabilities, net	(36,884)
Domestic [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets	68,723	48,265
Valuation Allowance	(64,054)	(48,265)
Deferred Tax Assets, net	4,669
International [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets		11,378
Deferred Tax Liabilities	(39,493)
Valuation Allowance	(2,060)	(2,299)
Deferred Tax Assets, net		$ 9,079
Deferred Tax Liabilities, net	$ (41,553)

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense Related to Stock Options, RSUs and Restricted Stock (Detail) shares in Thousands	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Share-Based Payment Arrangement [Abstract]
Number of Shares, Unvested RSUs and restricted stock outstanding, beginning balance | shares	1,930
Number of Shares, RSUs and restricted stock granted | shares	545
Number of Shares, RSUs and restricted stock vested | shares	(20)
Number of Shares, RSUs and restricted stock forfeited | shares	(46)
Number of Shares, Unvested RSUs and restricted stock outstanding, ending balance | shares	2,409
Weighted Avg. Grant Date Fair Value, Unvested RSUs and restricted stock outstanding, Beginning Balance | $ / shares	$ 14.11
Weighted Avg. Grant Date Fair Value, RSUs and restricted stock granted | $ / shares	19.96
Weighted Avg. Grant Date Fair Value, RSUs and restricted stock vested | $ / shares	13.67
Weighted Avg. Grant Date Fair Value, RSUs and restricted stock forfeited | $ / shares	14.18
Weighted Avg. Grant Date Fair Value, Unvested RSUs and restricted stock outstanding, Ending Balance | $ / shares	$ 17.36

Stock-Based Compensation (PSUs,

Stock-Based Compensation (PSUs, RSUs and Restricted Stock) - Additional Information (Detail) - USD ($) $ in Millions		9 Months Ended
	Jul. 15, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Jul. 22, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share granted		545,000
Recognition period of unvested compensation expense		2 years 8 months 12 days
Options available for issuance under stockholders-approved equity plan		3,400,000
ADVA Optical Networking SE, [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Recognition period of unvested compensation expense		1 year 1 month 6 days
Number of market based PSU awards converted to time based RSU awards	300,000
Options available for issuance under stockholders-approved equity plan					2,000,000
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options available for issuance under stockholders-approved equity plan		2,100,000
Performance Stock Units (PSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share granted		300,000	300,000
Vesting period		1 year	2 years	3 years
Performance Stock Units (PSUs) [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of performance stock units granted		0%	0%	0%
Performance Stock Units (PSUs) [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of performance stock units granted		142.80%	142.80%	142.80%
Market-Based PSUs, RSUs and Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to other than options		$ 24.6
Recognition period of unvested compensation expense		1 year 7 months 6 days
Time-Based RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to other than options	$ 17.8	$ 8.9
Recognition period of unvested compensation expense	3 months 18 days
Time-Based RSUs [Member] | ADVA Optical Networking SE, [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to other than options		$ 2.1
Recognition period of unvested compensation expense		1 year 1 month 6 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Options Outstanding (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands			3 Months Ended	9 Months Ended	12 Months Ended
		Jul. 15, 2022	Sep. 30, 2022	Sep. 30, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Stock Options, Stock options outstanding, Beginning Balance				1,721
Number of Stock Options, Stock options exercised				(439)
Number of Stock Options, Stock options forfeited				(12)
Number of Stock Options, Stock options expired				(70)
Number of Stock Options, Stock options outstanding, Ending Balance			3,180	3,180	1,721
Number of Stock Options, Stock options exercisable			1,627	1,627
Weighted Avg. Exercise Price, Stock options outstanding, Beginning Balance				$ 19.37
Weighted Avg. Exercise Price, Stock options exercised				16.16
Weighted Avg. Exercise Price, Stock options forfeited				11.08
Weighted Avg. Exercise Price, Stock options expired				26.38
Weighted Avg. Exercise Price, Stock options outstanding, Ending Balance			$ 14.58	14.58	$ 19.37
Weighted Avg. Exercise Price, Stock options exercisable			$ 16.85	$ 16.85
Weighted Avg. Remaining Contractual Life In Years, Stock options outstanding				3 years 6 months	2 years 4 months 24 days
Weighted Avg. Remaining Contractual Life in Years, Stock options exercisable				2 years
Aggregate Intrinsic Value, Stock options outstanding				$ 6,669
Aggregate Intrinsic Value, Stock options outstanding			$ 17,839	17,839	$ 6,669
Aggregate Intrinsic Value, Stock options exercisable			$ 6,375	$ 6,375
ADVA Optical Networking SE [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Stock Options, Stock options outstanding, Beginning Balance			2,745
Number of Stock Options, Stock options replaced	[1]		(2,403)	1,980
Number of Stock Options, Stock options exercised			(56)
Number of Stock Options, Stock options forfeited			(4)
Number of Stock Options, Stock options outstanding, Ending Balance		2,745	282	282
Number of Stock Options, Stock options exercisable			32	32
Weighted Avg. Exercise Price, Stock options outstanding, Beginning Balance			$ 9.09
Weighted Avg. Exercise Price, Stock options replaced	[1]		9.25	$ 11.16
Weighted Avg. Exercise Price, Stock options exercised			6.79
Weighted Avg. Exercise Price, Stock options forfeited			7.91
Weighted Avg. Exercise Price, Stock options outstanding, Ending Balance		$ 9.09	8.45	8.45
Weighted Avg. Exercise Price, Stock options exercisable			$ 7.72	$ 7.72
Weighted Avg. Remaining Contractual Life In Years, Stock options outstanding		4 years 7 months 6 days	3 years 10 months 24 days
Weighted Avg. Remaining Contractual Life in Years, Stock options exercisable			1 year 2 months 12 days
Aggregate Intrinsic Value, Stock options outstanding			$ 27,205
Aggregate Intrinsic Value, Stock options outstanding		$ 27,205	2,976	$ 2,976
Aggregate Intrinsic Value, Stock options exercisable			$ 363	$ 363
[1] Each ADVA stock option surrendered was exchanged for 0.8244 ADTRAN Holdings stock options.

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Options Outstanding (Parenthetical) (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022
ADVA Optical Networking SE, [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option surrendered, exchange ratio	0.8244	0.8244

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock Options) - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jul. 22, 2022	Jul. 15, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation expense		$ 12,100	$ 1,800	$ 15,900	$ 5,500
Unrecognized compensation expense related to stock options	$ 9,000	$ 9,000		$ 9,000
Recognition period of unvested compensation expense				2 years 8 months 12 days
Options available for issuance under stockholders-approved equity plan	3.4	3.4		3.4
Aggregate intrinsic value based on fair market value	$ 17,839	$ 17,839		$ 17,839				$ 6,669
Total pre-tax intrinsic value of options exercised				$ 3,400
Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options available for issuance under stockholders-approved equity plan	2.1	2.1		2.1
ADVA Optical Networking SE [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 300	$ 300		$ 300
Recognition period of unvested compensation expense				1 year 1 month 6 days
Options available for issuance under stockholders-approved equity plan						2
Aggregate intrinsic value based on fair market value	2,976	$ 2,976		$ 2,976			$ 27,205
Total pre-tax intrinsic value of options exercised	$ 700

Investments - Debt Securities a

Investments - Debt Securities and Other Investments, Included on Condensed Consolidated Balance Sheet and Recorded at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 30,117	$ 30,199
Gross Unrealized Gains		38
Gross Unrealized Losses	(1,454)	(171)
Fair Value	28,663	30,066
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,358	10,776
Gross Unrealized Gains		6
Gross Unrealized Losses	(374)	(35)
Fair Value	8,984	10,747
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,411	1,553
Gross Unrealized Gains		2
Gross Unrealized Losses	(54)	(4)
Fair Value	1,357	1,551
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,988	322
Gross Unrealized Gains		3
Gross Unrealized Losses	(77)	(3)
Fair Value	2,911	322
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,720	4,754
Gross Unrealized Gains		15
Gross Unrealized Losses	(280)	(33)
Fair Value	4,440	4,736
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,231	12,251
Gross Unrealized Gains		12
Gross Unrealized Losses	(642)	(92)
Fair Value	10,589	12,171
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	409	543
Gross Unrealized Losses	(27)	(4)
Fair Value	$ 382	$ 539

Investments - Contractual Matur

Investments - Contractual Maturities of Debt Securities and Other Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities, Fair Value/Carrying Value	$ 28,663	$ 30,066
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	96
One to two years	5,371
Two to three years	3,517
Available-for-sale debt securities, Fair Value/Carrying Value	8,984	10,747
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	525
One to two years	722
Two to three years	110
Available-for-sale debt securities, Fair Value/Carrying Value	1,357	1,551
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
One to two years	95
Two to three years	715
Three to five years	1,306
Five to ten years	382
More than ten years	413
Available-for-sale debt securities, Fair Value/Carrying Value	2,911	322
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than one year	182
One to two years	464
Two to three years	1,321
Three to five years	166
Five to ten years	810
More than ten years	1,497
Available-for-sale debt securities, Fair Value/Carrying Value	4,440	4,736
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
One to two years	7,421
Two to three years	2,889
Three to five years	279
Available-for-sale debt securities, Fair Value/Carrying Value	10,589	12,171
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
One to two years	275
Two to three years	107
Available-for-sale debt securities, Fair Value/Carrying Value	$ 382	$ 539

Investments - Gross Realized Ga

Investments - Gross Realized Gains and Losses on Sale of Debt Securities (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Gross realized gain on debt securities	$ 1	$ 22	$ 14	$ 206
Gross realized loss on debt securities	(116)	(17)	(242)	(53)
Total (loss) gain recognized, net	$ (115)	$ 5	$ (228)	$ 153

Investments - Additional Inform

Investments - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022	Sep. 30, 2021
Schedule of Investments [Line Items]
Available-for-sale debt securities, allowance for credit losses	$ 0	$ 0	$ 0
Purchase an available-for-sale debt securities with credit deterioration		0
Asset impairments	$ 16,969,000	$ 16,969,000
Investment [Member] | Issuer Concentration [Member] | Market Value of Total Investment Portfolio [Member]
Schedule of Investments [Line Items]
Investment concentration risk percentage		5%

Investments - Realized and Unre

Investments - Realized and Unrealized Gains and Losses related to Marketable Equity Securities (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Realized (loss) gain on equity securities sold	$ (1,358)		$ (1,675)	$ (55)
Unrealized (loss) gain on equity securities held	(1,217)	$ (68)	(8,849)	2,844
Total (loss) gain recognized, net	$ (2,575)	$ (68)	$ (10,524)	$ 2,789

Investments - Cash Equivalents

Investments - Cash Equivalents and Investments held at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	$ 28,663	$ 30,066
Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	51,632	70,259
Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	33,558	52,364
Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	18,074	17,895
Money Market Funds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	698	652
Money Market Funds [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	698	652
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	8,984	10,747
Corporate Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	8,984	10,747
Corporate Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	8,984	10,747
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	1,357	1,551
Municipal Fixed-Rate Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	1,357	1,551
Municipal Fixed-Rate Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	1,357	1,551
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	2,911	322
Asset-Backed Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	2,911	322
Asset-Backed Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	2,911	322
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	4,440	4,736
Mortgage/Agency-Backed Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	4,440	4,736
Mortgage/Agency-Backed Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	4,440	4,736
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	10,589	12,171
U.S. Government Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	10,589	12,171
U.S. Government Bonds [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	10,589	12,171
Foreign Government Securities / Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	382	539
Foreign Government Securities / Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	382	539
Foreign Government Securities / Bonds [Member] | Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	382	539
Marketable Equity Securities - Various Industries [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	760	12,606
Marketable Equity Securities - Various Industries [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	760	12,606
Deferred Compensation Plan Assets [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	21,511	26,935
Deferred Compensation Plan Assets [Member] | Fair Value, Measurements [Member] | Quoted Prices in Active Market for Identical Assets (Level 1) [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	$ 21,511	$ 26,935

Inventory - Components of Inven

Inventory - Components of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Raw materials	$ 177,554	$ 74,709
Work in process	10,625	2,143
Finished goods	227,984	63,039
Total Inventory, net	$ 416,163	$ 139,891

Inventory - Additional Informat

Inventory - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Inventory valuation reserves	$ 51.3	$ 44.6

Property, Plant and Equipment -

Property, Plant and Equipment - Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Engineering and other equipment	$ 162,445	$ 134,771
Building	80,807	68,157
Computer hardware and software	79,990	72,274
Building and land improvements	40,132	35,578
Furniture and fixtures	20,891	19,917
Land	5,298	4,575
Other assets	4,835
Total property, plant and equipment	394,398	335,272
Less: accumulated depreciation	(289,821)	(279,506)
Total property, plant and equipment, net	$ 104,577	$ 55,766

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 104,577		$ 104,577		$ 55,766
Asset impairments	16,969		16,969
Depreciation	7,100	$ 3,000	12,600	$ 9,100
ADVA Optical Networking SE [Member]
Property, Plant and Equipment [Line Items]
Asset impairments	$ 17,000		$ 17,000

Goodwill - Summary of Changes i

Goodwill - Summary of Changes in Carrying Amount of Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
Goodwill [Line Items]
Goodwill, Beginning balance	$ 6,968
Foreign currency translation adjustment	(8,256)
Goodwill, Ending balance	357,869
ADVA Optical Networking SE, [Member]
Goodwill [Line Items]
Goodwill from Business Combination with ADVA	359,157
Goodwill, Ending balance	359,200
Network Solutions [Member]
Goodwill [Line Items]
Goodwill, Beginning balance	6,568
Foreign currency translation adjustment	(6,220)
Goodwill, Ending balance	270,916
Network Solutions [Member] | ADVA Optical Networking SE, [Member]
Goodwill [Line Items]
Goodwill from Business Combination with ADVA	270,568
Services & Support [Member]
Goodwill [Line Items]
Goodwill, Beginning balance	400
Foreign currency translation adjustment	(2,036)
Goodwill, Ending balance	86,953
Services & Support [Member] | ADVA Optical Networking SE, [Member]
Goodwill [Line Items]
Goodwill from Business Combination with ADVA	$ 88,589

Goodwill - Additional Informati

Goodwill - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Goodwill [Line Items]
Impairment of goodwill	$ 0	$ 0	$ 0	$ 0

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 431,623	$ 36,166
Accumulated Amortization	(38,048)	(16,873)
Net Book Value	$ 393,575	19,293
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	10 years 10 months 24 days
Gross Carrying Amount	$ 52,139	20,796
Accumulated Amortization	(11,207)	(9,906)
Net Book Value	$ 40,932	10,890
Backlog [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	1 year 4 months 24 days
Gross Carrying Amount	$ 50,966
Accumulated Amortization	(9,325)
Net Book Value	$ 41,641
Developed Technology [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	8 years 6 months
Gross Carrying Amount	$ 294,983	8,200
Accumulated Amortization	(11,565)	(3,683)
Net Book Value	$ 283,418	4,517
Licensed Technology [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	9 years
Gross Carrying Amount	$ 5,900	5,900
Accumulated Amortization	(2,977)	(2,486)
Net Book Value	$ 2,923	3,414
Licensing Agreements [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	8 years 6 months
Gross Carrying Amount	$ 560	560
Accumulated Amortization	(280)	(225)
Net Book Value	$ 280	335
Patent [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	7 years 3 months 18 days
Gross Carrying Amount	$ 500	500
Accumulated Amortization	(414)	(363)
Net Book Value	$ 86	137
Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	2 years 9 months 18 days
Gross Carrying Amount	$ 26,575	210
Accumulated Amortization	(2,280)	(210)
Net Book Value	$ 24,295

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Impairment losses of long-lived assets			$ 0	$ 0
Impairment losses of intangible assets	$ 0	$ 0	0	0
Amortization expense	$ 20,400,000	$ 1,000,000	$ 22,200,000	$ 3,100,000

Intangible Assets - Estimated F

Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2022	$ 23,691
2023	75,677
2024	53,021
2025	42,623
2026	39,505
Thereafter	159,058
Net Book Value	$ 393,575	$ 19,293

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Lessee, Lease, Description [Line Items]
Operating lease, option to extend, existence			true
Operating lease, option to terminate, existence			true
Variable lease cost	$ 0.2	$ 0.1	$ 0.5	$ 0.4
Future operating lease payments relating to extension of lease term	$ 4.5		4.5
Cash used in operating activities related to operating leases			$ 2.3	1.4
Minimum [Member]
Lessee, Lease, Description [Line Items]
Operating lease, remaining lease terms	1 month		1 month
Operating lease, options to terminate term			3 months
Maximum [Member]
Lessee, Lease, Description [Line Items]
Operating lease, remaining lease terms	78 months		78 months
Operating lease, renewal term	5 years		5 years
Short-term lease cost	$ 0.1	$ 0.1	$ 0.1	$ 0.1

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Balance Sheet Information Related to Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets [Abstract]
Operating lease assets	$ 28,081	$ 4,922
Operating lease, right-of-use asset, statement of financial position [extensible list]	Other non-current assets	Other non-current assets
Liabilities [Abstract]
Current operating lease liability	$ 6,604	$ 1,730
Operating lease, liability, current, statement of financial position [extensible list]	Accrued expenses and other liabilities	Accrued expenses and other liabilities
Non-current operating lease liability	$ 21,490	$ 3,269
Operating lease, liability, noncurrent, statement of financial position [extensible list]	Non-current lease obligations	Non-current lease obligations
Total lease liability	$ 28,094	$ 4,999

Leases - Components of Lease Ex

Leases - Components of Lease Expense included in Consolidated Statements of Loss (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Lessee, Lease, Description [Line Items]
Total operating lease expense	$ 1,692	$ 471	$ 2,482	$ 1,498
Selling, General and Administrative Expenses [Member]
Lessee, Lease, Description [Line Items]
Total operating lease expense	1,444	196	1,704	645
Research and Development Expense [Member]
Lessee, Lease, Description [Line Items]
Total operating lease expense	228	261	719	815
Cost of Sales [Member]
Lessee, Lease, Description [Line Items]
Total operating lease expense	$ 20	$ 14	$ 59	$ 38

Leases - Schedule of Maturity o

Leases - Schedule of Maturity of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Lessee, Operating Lease, Liability, to be Paid [Abstract]
2022	$ 2,209
2023/2022	8,421	$ 1,767
2024/2023	7,098	1,419
2025/2024	5,838	1,188
2026/2025	3,354	710
Thereafter	5,107
Total lease payments	32,027	5,084
Less: Interest	(3,933)	(85)
Total lease liability	$ 28,094	$ 4,999

Leases - Schedule of Weighted A

Leases - Schedule of Weighted Average Remaining Lease Terms and Weighted Average Discount Rates (Details)	Sep. 30, 2022
USD
Weighted average remaining lease term (years)
Operating leases with functional currency	1 year 7 months 6 days
Weighted average discount rate
Operating leases with functional currency	3.93%
EUR
Weighted average remaining lease term (years)
Operating leases with functional currency	4 years 6 months
Weighted average discount rate
Operating leases with functional currency	4.05%

Leases - Net Investment in Sale

Leases - Net Investment in Sales-Type Leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Sales-Type Lease, Net Investment in Lease, before Allowance for Credit Loss [Abstract]
Current minimum lease payments receivable	$ 11	$ 92
Non-current minimum lease payments receivable		4
Total minimum lease payments receivable	11	96
Less: Current unearned revenue	5	70
Less: Non-current unearned revenue		1
Net investment in sales-type leases	$ 6	$ 25

Revolving Credit Agreements - C

Revolving Credit Agreements - Carrying Amount of Revolving Agreements (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Aug. 08, 2022
Line of Credit Facility [Line Items]
Revolving credit agreements	$ 84,503
Wells Fargo Credit Agreement [Member]
Line of Credit Facility [Line Items]
Revolving credit agreements	60,000
Nord/LB Revolving Line of Credit [Member]
Line of Credit Facility [Line Items]
Revolving credit agreements	14,702	$ 14,700
Syndicated Credit Agreement Working Capital Line of Credit [Member]
Line of Credit Facility [Line Items]
Revolving credit agreements	$ 9,801

Revolving Credit Agreements - A

Revolving Credit Agreements - Additional Information (Detail) $ in Thousands			1 Months Ended			9 Months Ended
	Aug. 08, 2022 USD ($)	Aug. 05, 2022	Dec. 31, 2024	Sep. 30, 2024	Oct. 31, 2019 USD ($)	Sep. 30, 2022 USD ($)	Jul. 18, 2022 USD ($)	May 19, 2022 USD ($)	Apr. 01, 2022 USD ($)	Sep. 30, 2018 USD ($)
Line Of Credit Facility [Line Items]
Weighted average interest rate						4.05%
Repayment of debt under revolving credit agreements						$ 48,000
Revolving line of credit						$ 84,503
Debt instrument default interest rate percentage						2%
Daily Simple SOFR [Member]
Line Of Credit Facility [Line Items]
Credit facility, floor rate						0%
EURIBOR [Member]
Line Of Credit Facility [Line Items]
Credit facility, floor rate						0%
Maximum [Member] | Daily Simple SOFR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate						2.15%
Maximum [Member] | Base Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate						1.25%
Maximum [Member] | EURIBOR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate						2.25%
Minimum [Member] | Daily Simple SOFR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate						1.40%
Minimum [Member] | Base Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate						0.50%
Minimum [Member] | EURIBOR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate						1.50%
Wells Fargo Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Revolving line of credit						$ 60,000
Line of credit facility maturity and frequency of payment and borrowing frequency						in tranches that mature during the fourth quarter of 2022 and can either be repaid or borrowed again for a one month, three month or six month period
Commitment fee percentage						0.25%
Net leverage ratio		3
Line of credit maturity period month and year						2027-07
Wells Fargo Credit Agreement [Member] | Daily Simple SOFR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate						1%
Wells Fargo Credit Agreement [Member] | Federal Reserve Bank Advances [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate						1%
Syndicated Credit Agreement Working Capital Line of Credit [Member]
Line Of Credit Facility [Line Items]
Revolving line of credit						$ 9,801
Nord/LB Revolving Line of Credit [Member]
Line Of Credit Facility [Line Items]
Revolving line of credit	$ 14,700					14,702
Available for future borrowings						0
Line of credit maturity period month and year	2023-08
Debt cover ratio	2.75
Nord/LB Revolving Line of Credit [Member] | Euro Short Term Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate	1.40%
Acorn HoldCo, Inc., [Member] | Wells Fargo Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Secured revolving credit facility amount						100,000	$ 100,000
New secured revolving credit facility amount						100,000	$ 100,000
Revolving line of credit						60,000
Credit facility, average outstanding amount						16,000
Letters of credit may be issued						25,000
Available for future borrowings						24,000
Acorn HoldCo, Inc., [Member] | Wells Fargo Credit Agreement [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Credit agreement current borrowing capacity						400,000
Cadence Bank, N.A [Member] | Secured Revolving Credit Facility [Member] | Revolving Credit and Security Agreement (The "Cadence Revolving Credit Agreement") [Member]
Line Of Credit Facility [Line Items]
Secured revolving credit facility amount								$ 25,000
New secured revolving credit facility amount								$ 25,000
Repayment of debt under revolving credit agreements						18,000
Wells Fargo Bank [Member] | Secured Revolving Credit Facility [Member] | Revolving Credit and Security Agreement (The "Cadence Revolving Credit Agreement") [Member]
Line Of Credit Facility [Line Items]
Repayment of debt under revolving credit agreements						10,000
Wells Fargo Bank [Member] | Secured Revolving Credit Facility [Member] | Credit Agreement and Revolving Line of Credit Note (The "Wells Revolving Credit Agreement") [Member]
Line Of Credit Facility [Line Items]
Secured revolving credit facility amount									$ 25,000
New secured revolving credit facility amount									$ 25,000
Deutsche Bank [Member]
Line Of Credit Facility [Line Items]
Revolving line of credit					$ 9,800
Deutsche Bank [Member] | EURIBOR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate					1.10%
Bayerische Landesbank and Deutsche Bank | Syndicated Credit Agreement Working Capital Line of Credit [Member]
Line Of Credit Facility [Line Items]
Secured revolving credit facility amount										$ 9,800
New secured revolving credit facility amount										$ 9,800
Revolving line of credit						9,800
Available for future borrowings						$ 0
Applicable margin rate						1.35%
Scenario Forecast [Member] | Wells Fargo Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Net leverage ratio			2.75	3.25

Notes Payable - Carrying Amount

Notes Payable - Carrying Amounts of Note Payables (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Debt Instrument [Line Items]
Fair Value	$ 29,611
Carrying Value	29,782
Syndicated Credit Agreement Note Payable [Member]
Debt Instrument [Line Items]
Fair Value	29,611
Carrying Value	$ 29,782

Notes Payable - Additional Info

Notes Payable - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Oct. 31, 2019	Sep. 30, 2022	Sep. 30, 2018
Debt Instrument [Line Items]
Revolving line of credit		$ 84,503
Notes Payable		29,782
Deutsche Bank [Member]
Debt Instrument [Line Items]
Revolving line of credit	$ 9,800
Deutsche Bank [Member] | EURIBOR [Member]
Debt Instrument [Line Items]
Applicable margin rate	1.10%
Syndicated Credit Agreement Note Payable [Member]
Debt Instrument [Line Items]
Notes Payable		$ 29,782
Syndicated Credit Agreement Note Payable [Member] | Bayerische Landesbank and Deutsche Bank [Member]
Debt Instrument [Line Items]
Notes payable borrowings			$ 63,700
Syndicated Credit Agreement Note Payable [Member] | Bayerische Landesbank and Deutsche Bank [Member] | EURIBOR [Member]
Debt Instrument [Line Items]
Applicable margin rate		1.35%

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 16,220	$ 11,402
Contributions to defined benefit pension plans	1,200
Defined benefit pension plans for the remainder of fiscal year	$ 600

Employee Benefit Plans - Schedu

Employee Benefit Plans - Schedule of the Components of Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 478	$ 307	$ 981	$ 931
Interest cost	204	84	638	257
Expected return on plan assets	(465)	(460)	(1,384)	(1,396)
Amortization of actuarial losses	81	272	254	825
Net periodic benefit cost	$ 298	$ 203	$ 489	$ 617

Equity - Additional Information

Equity - Additional Information (Detail) - shares	9 Months Ended
	Sep. 30, 2022	Jul. 15, 2022
Subsidiary or Equity Method Investee [Line Items]
Stock repurchased, shares	0
Maximum shares authorized for repurchase, prior and new announcements and total after new announcement	0
ADVA
Subsidiary or Equity Method Investee [Line Items]
Equity method ownership percentage	34.65%	34.57%

Equity - Changes in Accumulated

Equity - Changes in Accumulated Other Comprehensive Loss, Net of Tax, by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 348,537	$ 375,515	$ 357,102	$ 372,944
Other comprehensive loss before reclassifications	(23,426)	(1,418)	(28,748)	(3,272)
Amounts reclassified from accumulated other comprehensive (loss) income	(260)	92	280	445
Net current period other comprehensive (loss) income	(23,686)	(1,326)	(28,468)	(2,827)
Less: Comprehensive Loss attributable to non-controlling interest, net of tax	(94)		(94)
Ending Balance	1,184,827	363,753	1,184,827	363,753
ASU 2018-02 [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	385	385	385	385
Ending Balance	385	385	385	385
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(16,696)	(13,140)	(11,914)	(11,639)
Ending Balance	(40,288)	(14,466)	(40,288)	(14,466)
Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,476)	(255)	(552)	32
Other comprehensive loss before reclassifications	(254)	(29)	(1,818)	(358)
Amounts reclassified from accumulated other comprehensive (loss) income	(142)	(32)	498	10
Net current period other comprehensive (loss) income	(396)	(61)	(1,320)	(348)
Ending Balance	(1,872)	(316)	(1,872)	(316)
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(5,713)	(9,310)	(5,613)	(9,621)
Amounts reclassified from accumulated other comprehensive (loss) income	118	124	(218)	435
Net current period other comprehensive (loss) income	118	124	(218)	435
Ending Balance	(5,831)	(9,186)	(5,831)	(9,186)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(9,892)	(3,960)	(6,134)	(2,435)
Other comprehensive loss before reclassifications	(23,172)	(1,389)	(26,930)	(2,914)
Net current period other comprehensive (loss) income	(23,172)	(1,389)	(26,930)	(2,914)
Less: Comprehensive Loss attributable to non-controlling interest, net of tax	(94)		(94)
Ending Balance	$ (32,970)	$ (5,349)	$ (32,970)	$ (5,349)

Equity - Reclassifications Out

Equity - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss Before Income Taxes	$ (49,171)	$ (9,135)	$ (48,415)	$ (978)
Tax benefit (expense)	4,312	(1,292)	4,572	(3,467)
Net Loss attributable to ADTRAN Holdings, Inc.	(41,934)	(10,427)	(40,918)	(4,445)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss Before Income Taxes	358	(138)	(339)	(643)
Tax benefit (expense)	(98)	46	59	198
Net Loss attributable to ADTRAN Holdings, Inc.	260	(92)	(280)	(445)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member] | Unrealized Gains (Losses) on Available-for-Sale Securities [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net investment (loss) gain	187	42	(655)	(13)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member] | Other Income (Expense), Net [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined benefit plan adjustments - actuarial gain (loss)	$ (171)	$ (180)	$ 316	$ (630)

Equity - Tax Effects Related to

Equity - Tax Effects Related to the Change in Each Component of Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Equity [Abstract]
Unrealized gain (loss) on available-for-sale securities, Before-Tax Amount	$ (334)			$ (38)			$ (2,392)	$ (471)
Unrealized gain (loss) on available-for-sale securities, Tax (Expense) Benefit	80			9			574	113
Unrealized gain (loss) on available-for-sale securities, Net-of-Tax Amount	(254)			(29)			(1,818)	(358)
Reclassification adjustment for amounts related to available-for-sale investments included in net loss, Before-Tax Amount	(187)			(42)			655	13
Reclassification adjustment for amounts related to available-for-sale investments included in net loss, Tax (Expense) Benefit	45			10			(157)	(3)
Reclassification adjustment for amounts related to available-for-sale investments included in net loss, Net-of-Tax Amount	(142)			(32)			498	10
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net loss, Before-Tax Amount	171			180			(316)	630
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net loss, Tax (Expense) Benefit	(53)			(56)			98	(195)
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net loss, Net-of-Tax Amount	118			124			(218)	435
Foreign currency translation adjustment, Before-Tax Amount	(23,172)			(1,389)			(26,930)	(2,914)
Foreign currency translation adjustment, Net-of-Tax Amount	(23,172)			(1,389)			(26,930)	(2,914)
Total Other Comprehensive Income (Loss), Before-Tax Amount	(23,864)			(1,289)			(28,983)	(2,742)
Total Other Comprehensive Income (Loss), Tax (Expense) Benefit	178			(37)			515	(85)
Other Comprehensive Loss, net of tax	$ (23,686)	$ (3,140)	$ (1,642)	$ (1,326)	$ 455	$ (1,956)	$ (28,468)	$ (2,827)

Loss Per Share - Summary of Cal

Loss Per Share - Summary of Calculation of Basic and Diluted Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Numerator
Net loss attributable to ADTRAN Holdings, Inc.	$ (41,934)	$ (10,427)	$ (40,918)	$ (4,445)
Denominator
Weighted average number of shares – basic	73,036	48,609	57,175	48,470
Effect of dilutive securities
Weighted average number of shares – diluted	73,036	48,609	57,175	48,470
Loss per share attributable to ADTRAN Holdings, Inc.- basic	$ (0.57)	$ (0.21)	$ (0.72)	$ (0.09)
Loss per share attributable to ADTRAN Holdings, Inc. - diluted	$ (0.57)	$ (0.21)	$ (0.72)	$ (0.09)

Loss Per Share - Additional Inf

Loss Per Share - Additional Information (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive effect excluded calculation of diluted earnings per share	100	200	200	400
Unvested Stock Options, PSUs, RSUs and Restricted Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive effect excluded calculation of diluted earnings per share	4		4	4
Unvested Stock Options, PSUs, RSUs and Restricted Stock [Member] | Maximum [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive effect excluded calculation of diluted earnings per share		1

Segment Information - Additiona

Segment Information - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2022 Segment Category
Segment Reporting [Abstract]
Number of reportable segments | Segment	2
Number of categories | Category	3

Segment Information - Revenue a

Segment Information - Revenue and Gross Profit of Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenue	$ 340,709	$ 138,081	$ 667,265	$ 408,846
Gross Profit	103,027	47,673	219,849	163,942
Network Solutions [Member]
Segment Reporting Information [Line Items]
Revenue	304,940	120,767	599,306	360,025
Gross Profit	82,334	39,738	186,126	143,981
Services & Support [Member]
Segment Reporting Information [Line Items]
Revenue	35,769	17,314	67,959	48,821
Gross Profit	$ 20,693	$ 7,935	$ 33,723	$ 19,961

Segment Information - Revenue I

Segment Information - Revenue Information by Category (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation Of Revenue [Line Items]
Revenue	$ 340,709	$ 138,081	$ 667,265	$ 408,846
Subscriber Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	133,675	46,867	270,147	152,489
Access & Aggregation Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	88,189	$ 91,214	278,273	$ 256,357
Optical Networking Solutions
Disaggregation Of Revenue [Line Items]
Revenue	$ 118,845		$ 118,845

Segment Information - Revenue_2

Segment Information - Revenue Information by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenue from External Customer [Line Items]
Revenue	$ 340,709	$ 138,081	$ 667,265	$ 408,846
United States [Member]
Revenue from External Customer [Line Items]
Revenue	169,669	91,868	374,470	273,009
United Kingdom [Member]
Revenue from External Customer [Line Items]
Revenue	64,234	12,504	123,477	34,006
Germany [Member]
Revenue from External Customer [Line Items]
Revenue	46,569	17,782	71,945	50,737
Other International [Member]
Revenue from External Customer [Line Items]
Revenue	$ 60,237	$ 15,927	$ 97,373	$ 51,094

Liability for Warranty Return_2

Liability for Warranty Returns - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Product Warranties Disclosures [Abstract]
Period of assurance-based warranty for product defects	90 days to five years
Liability for warranty obligations	$ 8,601	$ 4,842	$ 5,403	$ 5,647	$ 5,997	$ 7,146

Liability for Warranty Return_3

Liability for Warranty Returns - Summary of Warranty Expense and Write-off Activity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Product Warranties Disclosures [Abstract]
Balance at beginning of period	$ 4,842	$ 5,997	$ 5,403	$ 7,146
Plus: ADVA acquisition	3,756		3,756
Plus: Amounts charged to cost and expenses	616	472	1,727	253
Less: Deductions	(613)	(822)	(2,285)	(1,752)
Balance at end of period	$ 8,601	$ 5,647	$ 8,601	$ 5,647

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Contingencies And Commitments [Line Items]
Commitments related to performance bonds	$ 21.1	$ 22.9
Commitments related to performance bonds expiration month and year	2025-04
Purchase commitments	$ 454.1
Commitments towards private equity funds	4.9
Investment Commitments [Member]
Contingencies And Commitments [Line Items]
Aggregate investment committed in private equity funds	$ 5

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) $ / shares in Units, $ in Millions					9 Months Ended
	Nov. 07, 2022 $ / shares	Oct. 18, 2022 $ / shares shares	Jul. 15, 2022 shares	Aug. 30, 2021	Sep. 30, 2022 shares	Dec. 31, 2022 USD ($)	Nov. 03, 2022 USD ($)	Oct. 18, 2022 € / shares	Dec. 31, 2021 shares
Subsequent Event [Line Items]
Exchange offer settled date			Jul. 15, 2022
Common stock, shares outstanding | shares					77,619,000				49,063,000
Scenario Forecast [Member]
Subsequent Event [Line Items]
Quarterly dividend payable, aggregate amount | $						$ 7
Subsequent Event [Member]
Subsequent Event [Line Items]
Common stock dividends per share declared | $ / shares	$ 0.09
Subsequent Event [Member] | DPLTA [Member]
Subsequent Event [Line Items]
Percentage of required voting interest		75%						75%
Subsequent Event [Member] | Cross-Currency Swap Arrangement [Member]
Subsequent Event [Line Items]
Aggregate notional amount | $							$ 160
Subsequent Event [Member] | Cross-Currency Swap Arrangement [Member] | Maximum [Member]
Subsequent Event [Line Items]
Aggregate notional amount, daily fixed forward conversion rate							0.98286
Subsequent Event [Member] | Cross-Currency Swap Arrangement [Member] | Minimum [Member]
Subsequent Event [Line Items]
Aggregate notional amount, daily fixed forward conversion rate							1.03290
Subsequent Event [Member] | Cross-Currency Swap Arrangement [Member] | Eight Quarterly Tranches [Member]
Subsequent Event [Line Items]
Aggregate notional amount | $							$ 20
ADVA Optical Networking SE [Member] | Subsequent Event [Member] | Maximum [Member]
Subsequent Event [Line Items]
Number of additional shares authorized to purchase | shares		15,346,544
ADVA Optical Networking SE [Member] | Subsequent Event [Member] | DPLTA [Member]
Subsequent Event [Line Items]
Price per share | $ / shares		$ 17.21
Annual recurring compensation per share								€ 0.59
Annual recurring compensation net per share								€ 0.52
ADVA Optical Networking SE [Member] | Subsequent Event [Member] | DPLTA [Member] | Annuity Interest Rate 3.00% [Member]
Subsequent Event [Line Items]
Annual recurring compensation per share | $ / shares		0.59
Annual recurring compensation net per share | $ / shares		$ 0.52
Annuity interest rate		3%						3%
ADVA Optical Networking SE [Member] | Subsequent Event [Member] | DPLTA [Member] | Annuity Interest Rate 3.25% [Member]
Subsequent Event [Line Items]
Annual recurring compensation per share								€ 0.62
Annual recurring compensation net per share								€ 0.54
Annuity interest rate		3.25%						3.25%
ADVA Optical Networking SE [Member] | Subsequent Event [Member] | DPLTA [Member] | Annuity Interest Rate 5.50% [Member]
Subsequent Event [Line Items]
Annual recurring compensation per share								€ 1
Annual recurring compensation net per share								€ 0.87
Annuity interest rate		5.50%						5.50%
Acorn HoldCo, Inc., [Member]
Subsequent Event [Line Items]
Business Acquisition, Date of Acquisition Agreement				Aug. 30, 2021
Number of shares subject to additional assumed options | shares			100,000
Common stock, shares outstanding | shares			34,000,000		33,957,538
Percentage of outstanding bearer shares			65.43%		65.35%