ADTRAN (ADTN) 10-Q 9 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Nov. 03, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
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		78,698,999
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, 2023	Dec. 31, 2022
Current Assets
Cash and cash equivalents	$ 116,092	$ 108,644
Short-term investments (includes $0 and $340 of available-for-sale securities as of September 30, 2023 and December 31, 2022, respectively, reported at fair value)		340
Accounts receivable, less allowance for credit losses of $15 and $49 as of September 30, 2023 and December 31, 2022, respectively	229,333	279,435
Other receivables	24,337	32,831
Inventory, net	373,971	427,531
Prepaid expenses and other current assets	35,826	33,577
Total Current Assets	779,559	882,358
Property, plant and equipment, net	118,623	110,699
Deferred tax assets	90,260	67,839
Goodwill	339,083	381,724
Intangibles, net	328,695	401,211
Other non-current assets	60,770	66,998
Long-term investments (includes $0 and $8,913 of available-for-sale securities as of September 30, 2023 and December 31, 2022, respectively, reported at fair value)	25,179	32,665
Total Assets	1,742,169	1,943,494
Current Liabilities
Accounts payable	148,913	237,699
Revolving credit agreements outstanding	10,580	35,936
Notes Payable		24,598
Unearned revenue	49,832	41,193
Accrued expenses and other liabilities	29,708	35,235
Accrued wages and benefits	35,957	44,882
Income tax payable, net	10,302	9,032
Total Current Liabilities	285,292	428,575
Non-current revolving credit agreement outstanding	200,000	60,000
Deferred tax liabilities	37,977	61,629
Non-current unearned revenue	23,501	19,239
Pension liability	10,732	10,624
Deferred compensation liability	26,833	26,668
Non-current lease obligations	23,612	22,807
Other non-current liabilities	17,408	10,339
Total Liabilities	625,355	639,881
Commitments and contingencies (see Note 20)
Redeemable Non-Controlling Interest	431,921
Equity
Common stock, par value $0.01 per share; 200,000 shares authorized; 78,688 shares issued and 78,391 outstanding as of September 30, 2023 and 78,088 shares issued and 77,889 shares outstanding as of December 31, 2022	787	781
Additional paid-in capital	770,565	895,834
Accumulated other comprehensive income	32,800	46,713
Retained (deficit) earnings	(113,289)	55,338
Treasury stock at cost: 297 and 198 shares as of September 30, 2023 and December 31, 2022, respectively	(5,970)	(4,125)
Non-controlling interest		309,072
Total Equity	684,893	1,303,613
Total Liabilities, Redeemable Non-Controlling Interest and Equity	$ 1,742,169	$ 1,943,494

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Short-term investments, available-for-sale securities at fair value	$ 0	$ 340
Accounts receivable, allowance for credit losses	15	49
Long-term investments, available-for-sale securities fair value	$ 0	$ 8,913
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	78,688,000	78,088,000
Common stock, shares outstanding	78,391,000	77,889,000
Treasury stock, shares	297,000	198,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Loss (Unaudited) - USD ($) shares in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue
Total Revenue		$ 272,331,000	$ 340,709,000	$ 923,621,000	$ 667,265,000
Cost of Revenue
Total Cost of Revenue		198,094,000	237,682,000	669,023,000	447,416,000
Gross Profit		74,237,000	103,027,000	254,598,000	219,849,000
Selling, general and administrative expenses		62,907,000	74,880,000	196,887,000	130,646,000
Research and development expenses		62,752,000	59,196,000	203,493,000	112,187,000
Asset impairment		0	16,969,000	0	16,969,000
Goodwill impairment		37,874,000		37,874,000
Operating Loss		(89,296,000)	(48,018,000)	(183,656,000)	(39,953,000)
Interest and dividend income		521,000	347,000	1,183,000	768,000
Interest expense		(4,507,000)	(1,303,000)	(11,858,000)	(1,427,000)
Net investment (loss) gain		(1,443,000)	(2,691,000)	1,071,000	(10,752,000)
Other income, net		2,523,000	2,494,000	4,714,000	2,949,000
Loss Before Income Taxes		(92,202,000)	(49,171,000)	(188,546,000)	(48,415,000)
Income tax benefit		16,553,000	4,312,000	36,229,000	4,572,000
Net Loss		(75,649,000)	(44,859,000)	(152,317,000)	(43,843,000)
Less: Net Loss attributable to non-controlling interest	[1]	(2,914,000)	(2,925,000)	(11,784,000)	(2,925,000)
Net Loss attributable to ADTRAN Holdings, Inc.		$ (72,735,000)	$ (41,934,000)	$ (140,533,000)	$ (40,918,000)
Weighted average shares outstanding – basic		78,389	73,036	78,378	57,175
Weighted average shares outstanding – diluted		78,389	73,036	78,378	57,175
Loss per common share attributable to ADTRAN Holdings, Inc. - basic		$ (0.93)	$ (0.57)	$ (1.79)	$ (0.72)
Loss per common share attributable to ADTRAN Holdings, Inc. - diluted		$ (0.93)	$ (0.57)	$ (1.79)	$ (0.72)
Network Solutions [Member]
Revenue
Total Revenue		$ 228,564,000	$ 304,940,000	$ 793,984,000	$ 599,306,000
Cost of Revenue
Total Cost of Revenue		160,244,000	222,606,000	596,334,000	413,180,000
Gross Profit		47,277,000	82,334,000	176,607,000	186,126,000
Network Solutions - Inventory Write Down [Member]
Cost of Revenue
Total Cost of Revenue		21,043,000		21,043,000
Services & Support [Member]
Revenue
Total Revenue		43,767,000	35,769,000	129,637,000	67,959,000
Cost of Revenue
Total Cost of Revenue		16,807,000	15,076,000	51,646,000	34,236,000
Gross Profit		26,960,000	$ 20,693,000	$ 77,991,000	$ 33,723,000
Goodwill impairment		$ 37,900,000
[1] (1)For the three and nine months ended September 30, 2023, we have recog nized $ 2.9 million and $ 8.6 mi llion, respectively, representing the recurring cash compensation earned by non-controlling interest shareholders post-DPLTA and an incremen tal $ 3.2 millio n net loss attributable to non-controlling interests pre-DPLTA for the nine months ended September 30, 2023.

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Loss (Unaudited) (Parenthetical) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)		Sep. 30, 2023 USD ($)
Net loss attributable to non-controlling interest	$ (2,914)	[1]	$ (11,784)	[1]
Annual recurring compensation earned	(8,605)		(8,605)
Pre-DPLTA [Member]
Net loss attributable to non-controlling interest			3,200
Post-DPLTA [Member]
Recurring cash compensation earned	$ 2,900		$ 8,600
[1] (1)For the three and nine months ended September 30, 2023, we have recog nized $ 2.9 million and $ 8.6 mi llion, respectively, representing the recurring cash compensation earned by non-controlling interest shareholders post-DPLTA and an incremen tal $ 3.2 millio n net loss attributable to non-controlling interests pre-DPLTA for the nine months ended September 30, 2023.

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (75,649)	$ (44,859)	$ (152,317)	$ (43,843)
Other Comprehensive Loss, net of tax
Net unrealized gain (loss) on available-for-sale securities	(391)	(396)	454	(1,320)
Defined benefit plan adjustments	(83)	(118)	(25)	(218)
Foreign currency translation loss	(29,716)	(23,172)	(14,098)	(26,930)
Other Comprehensive Loss, net of tax	(29,408)	(23,686)	(13,669)	(28,468)
Less: Comprehensive (Loss) Income attributable to non-controlling interest, net of tax		(94)	244	(94)
Comprehensive Loss attributable to ADTRAN Holdings, Inc., net of tax	$ (105,057)	$ (68,451)	$ (166,230)	$ (72,217)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Adtran Networks SE [Member]	Common Stock [Member]	Common Stock [Member] Adtran Networks SE [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Adtran Networks SE [Member]	Retained (Deficit) Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Non-controlling Interest [Member]	Non-controlling Interest [Member] Adtran Networks SE [Member]
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
Net (loss) income	(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)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested	(54)						(895)	841
ADTRAN Stock options exercised	568						(143)	711
ADTRAN 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
Other comprehensive income (loss), net of tax	(28,468)
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
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 (loss) income	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
ADTRAN RSUs, PSUs, RSUs and restricted stock vested	(300)						(90)	(210)
ADTRAN Stock options exercised	68						(19)	87
ADTRAN 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 (loss) income	(44,859)						(41,934)			(2,925)
Acquisition of Adtran Networks		$ 894,675		$ 280		$ 577,980					$ 316,415
Acquisition of Adtran Networks, 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)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested	(40)						(40)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested, Shares			4
ADTRAN Stock options exercised	4,433	365	$ 2			236	4,431				129
ADTRAN Stock options exercised, Shares			298
ADTRAN Stock-based compensation expense	11,195	938			11,195	885					53
Reclassification of Adtran Networks 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
Beginning Balance at Dec. 31, 2022	$ 1,303,613		$ 781		895,834		55,338	(4,125)	46,713	309,072
Beginning Balance, Shares at Dec. 31, 2022	78,088		78,088
Net (loss) income	$ (40,453)						(37,274)			(3,179)
Reclassification and remeasurement from equity to mezzanine equity for non-controlling interests in Adtran Networks	(443,757)					(137,620)					$ (306,137)
Other comprehensive income (loss), net of tax	8,782								8,538	244
Dividend payments ($0.09 per share)	(7,076)						(7,076)
Deferred compensation adjustments, net of tax	(1,792)							(1,792)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested	(138)		$ 6				(144)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested, Shares			561
ADTRAN Stock options exercised	58						58
ADTRAN Stock options exercised, Shares			6
ADTRAN Stock-based compensation expense	3,812	$ 9			3,812	9
Redemption of redeemable non-controlling interest	343						343
Foreign currency remeasurement of redeemable non-controlling interest	(430)						(430)
Annual recurring compensation earned	(2,809)						(2,809)
Ending Balance at Mar. 31, 2023	820,162		$ 787		762,035		8,006	(5,917)	55,251
Ending Balance, Shares at Mar. 31, 2023			78,655
Beginning Balance at Dec. 31, 2022	$ 1,303,613		$ 781		895,834		55,338	(4,125)	46,713	$ 309,072
Beginning Balance, Shares at Dec. 31, 2022	78,088		78,088
Other comprehensive income (loss), net of tax	$ (13,669)
ADTRAN Stock options exercised, Shares	8	13
Ending Balance at Sep. 30, 2023	$ 684,893		$ 787		770,565		(113,289)	(5,970)	32,800
Ending Balance, Shares at Sep. 30, 2023	78,688		78,688
Beginning Balance at Mar. 31, 2023	$ 820,162		$ 787		762,035		8,006	(5,917)	55,251
Beginning Balance, Shares at Mar. 31, 2023			78,655
Net (loss) income	(36,215)						(36,215)
Other comprehensive income (loss), net of tax	6,957								6,957
Dividend payments ($0.09 per share)	(7,076)						(7,076)
Dividends accrued for RSUs	9						9
Deferred compensation adjustments, net of tax	(26)							(26)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested	(44)						(44)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested, Shares			6
ADTRAN Stock options exercised		$ 92				92
ADTRAN Stock-based compensation expense	4,291	10			4,291	10
Redemption of redeemable non-controlling interest	6						6
Foreign currency remeasurement of redeemable non-controlling interest	(2,814)						(2,814)
Annual recurring compensation earned	(2,882)						(2,882)
Ending Balance at Jun. 30, 2023	782,470		$ 787		766,428		(41,010)	(5,943)	62,208
Ending Balance, Shares at Jun. 30, 2023			78,661
Net (loss) income	(75,649)						(75,649)
Other comprehensive income (loss), net of tax	(29,408)								(29,408)
Dividend payments ($0.09 per share)	(7,085)						(7,085)
Dividends accrued for RSUs	(8)						(8)
Deferred compensation adjustments, net of tax	(27)							(27)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested	(175)						(175)
ADTRAN RSUs, PSUs, RSUs and restricted stock vested, Shares			25
ADTRAN Stock options exercised	15	8				8	15
ADTRAN Stock options exercised, Shares			2
ADTRAN Stock-based compensation expense	4,126	$ 3			4,126	$ 3
Redemption of redeemable non-controlling interest	2						2
Foreign currency remeasurement of redeemable non-controlling interest	13,535						13,535
Annual recurring compensation earned	(2,914)						(2,914)
Ending Balance at Sep. 30, 2023	$ 684,893		$ 787		$ 770,565		$ (113,289)	$ (5,970)	$ 32,800
Ending Balance, Shares at Sep. 30, 2023	78,688		78,688

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Statement of Stockholders' Equity [Abstract]
Dividend payments	$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.09

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net loss	$ (152,317,000)	$ (43,843,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	91,422,000	34,783,000
Asset impairment	0	16,969,000
Goodwill impairment	37,874,000
Amortization of debt issuance cost	607,000	200,000
(Gain) loss on investments, net	(3,316,000)	10,395,000
Stock-based compensation expense	12,229,000	15,912,000
Deferred income taxes	(45,941,000)	(26,366,000)
Other, net	204,000	32,000
Inventory write down	21,043,000	0
Inventory reserves	29,836,000	(6,681,000)
Changes in operating assets and liabilities:
Accounts receivable, net	47,347,000	(34,535,000)
Other receivables	8,340,000	(2,154,000)
Inventory	536,000	(76,293,000)
Prepaid expenses, other current assets and other assets	1,816,000	610,000
Accounts payable	(87,903,000)	70,381,000
Accrued expenses and other liabilities	6,476,000	(23,005,000)
Income taxes payable, net	2,433,000	20,862,000
Net cash used in operating activities	(29,314,000)	(42,733,000)
Cash flows from investing activities:
Purchases of property, plant and equipment	(33,674,000)	(10,141,000)
Proceeds from sales and maturities of available-for-sale investments	10,545,000	30,474,000
Purchases of available-for-sale investments	(807,000)	(22,215,000)
Proceeds from beneficial interests in securitized accounts receivable	1,178,000	1,294,000
Proceeds from disposals of property, plant and equipment		12,000
Acquisition of business, net of cash acquired		43,957,000
Net cash (used in) provided by investing activities	(22,758,000)	43,381,000
Cash flows from financing activities:
Tax withholdings related to stock-based compensation settlements	(6,331,000)	(515,000)
Proceeds from stock option exercises	187,000	5,434,000
Dividend payments	(21,237,000)	(15,859,000)
Proceeds from draw on revolving credit agreements	163,760,000	133,141,000
Repayment of revolving credit agreements	(49,233,000)	(48,000,000)
Non-controlling interest put option buyback	(1,196,000)
Payment of debt issuance cost	(708,000)	(3,015,000)
Repayment of notes payable	(24,931,000)	(10,057,000)
Net cash provided by financing activities	60,311,000	61,129,000
Net increase in cash and cash equivalents	8,239,000	61,777,000
Effect of exchange rate changes	(791,000)	(7,496,000)
Cash and cash equivalents, beginning of period	108,644,000	56,818,000
Cash and cash equivalents, end of period	116,092,000	111,099,000
Supplemental disclosure of cash financing activities:
Cash paid for interest	8,540,000	633,000
Cash used in operating activities related to operating leases	7,378,000	2,272,000
Supplemental disclosure of non-cash investing activities:
Right-of-use assets obtained in exchange for lease obligations	8,490,000	904,000
Purchases of property, plant and equipment included in accounts payable	$ 2,508,000	1,037,000
Adtran Networks common shares exchanged in acquisition		565,491,000
Adtran Networks options assumed in acquisition		12,769,000
Non-controlling interest related to Adtran Networks		$ 315,415,000

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (72,735)	$ (41,934)	$ (140,533)	$ (40,918)

Insider Trading Arrangements

Insider Trading Arrangements	9 Months Ended
	Sep. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	GENERAL ADTRAN Holdings, Inc. (“ADTRAN” or the “Company”) is a leading global provider of networking and communications platforms, software, systems and services focused on the broadband access market, serving a diverse domestic and international customer base in multiple countries that includes large, medium and small Service Providers, alternative Service Providers, such as utilities, municipalities and fiber overbuilders, cable/MSOs, SMBs and distributed enterprises. Our innovative solutions and services enable voice, data, video and internet-communications across a variety of network infrastructures and are currently in use by millions worldwide. We support our customers through our direct global sales organization and our distribution networks. Our success depends upon our ability to increase unit volume and market share through the introduction of new products and succeeding generations of products having optimal selling prices and increased functionality as compared to both the prior generation of a product and to the products of competitors in order to gain market share. To service our customers and grow revenue, we are continually conducting research and developing new products addressing customer needs and testing those products for the specific requirements of the particular customers. We offer a broad portfolio of flexible software and hardware network solutions and services that enable Service Providers to meet today’s service demands, while enabling them to transition to the fully converged, scalable, highly-automated, cloud-controlled voice, data, internet and video network of the future. In addition to our global headquarters in Huntsville, Alabama, and our European headquarters in Munich, Germany, we have sales and research and development facilities in strategic global locations. ADTRAN Holdings, Inc. solely owns ADTRAN, Inc. and is the majority shareholder of Adtran Networks (formerly ADVA Optical Networking SE). ADTRAN is a leading global provider of open, disaggregated networking and communications solutions. Adtran Networks is a global provider of network solutions for data, storage, voice and video services. The combined technology portfolio can best address current and future requirements, especially regarding the convergence of solutions at the network edge. Domination and Profit and Loss Transfer Agreement The DPLTA between the Company, as the controlling company, and Adtran Networks SE, as the controlled company, as executed on December 1, 2022, became effective on January 16, 2023, as a result of its registration with the commercial register ( Handelsregister ) of the local court ( Amtsgericht ) at the registered seat of Adtran Networks (Jena). Under the DPLTA, subject to certain limitations pursuant to applicable law and the specific terms of the DPLTA, (i) the Company is entitled to issue binding instructions to the management board of Adtran Networks, (ii) Adtran Networks will transfer its annual profit to the Company, subject to, among other things, the creation or dissolution of certain reserves, and (iii) the Company will generally absorb the annual net loss incurred by Adtran Networks. The obligation of Adtran Networks to transfer its annual profit to the Company applies for the first time to the profit, if any, generated in the Adtran Networks fiscal year 2023. The obligation of the Company to absorb Adtran Networks annual net loss applies for the first time to the loss, if any, generated in the Adtran Networks fiscal year 2023. Pursuant to the terms of the DPLTA, each Adtran Networks shareholder (other than the Company) has received an offer to elect either (1) to remain an Adtran Networks shareholder and receive from us an Annual Recurring Compensation payment, or (2) to receive Exit Compensation plus guaranteed interest. The guaranteed interest under the Exit Compensation is calculated from the effective date of the DPLTA to the date the shares are tendered, less any Annual Recurring Compensation paid. The guaranteed interest rate is 5.0 % plus a variable component (according to the German Civil Code) that was 3.12 % as of September 30, 2023. Assuming all the minority holders of currently outstanding Adtran Networks shares were to elect the second option, we would be obligated to make aggregate Exit Compensation payments, including guaranteed interest, of approximately € 325.3 million or approximately $ 344.2 million, based on an exchange rate as of September 30, 2023 and reflecting interest accrued through September 30, 2023 during the pendency of the appraisal proceedings discussed below. Shareholders electing the first option of Annual Recurring Compensation may later elect the second option. The opportunity for outside Adtran Networks shareholders to tender Adtran Networks shares in exchange for Exit Compensation had been scheduled to expire on March 16, 2023 . However, due to the appraisal proceedings that have been initiated in accordance with applicable German law, this time period for tendering shares has been extended pursuant to the German Stock Corporation Act ( Aktiengesetz ) and will end two months after the date on which a final decision in such appraisal proceedings has been published in the Federal Gazette ( Bundesanzeiger ). We are also obligated to absorb any annual net loss of Adtran Networks under the DPLTA. Additionally, our obligation to pay Annual Recurring Compensation under the DPLTA is a continuing payment obligation, which will amount to approximately € 10.6 million or $ 11.2 million (based on the current exchange rate) per year assuming none of the minority Adtran Networks shareholders were to elect Exit Compensation. The foregoing amounts do not reflect any potential increase in payment obligations that we may have depending on the outcome of ongoing appraisal proceedings in Germany. During the three and nine months ended September 30, 2023, we accrued $ 2.9 million and $ 8.6 million in Annual Recurring Compensation, which was reflected as a reduction to retained (deficit) earnings, respectively. On October 18, 2022, the Company's Board of Directors authorized the Company to purchase additional shares of Adtran Networks through open market purchases not to exceed 15,346,544 shares. For the three and nine months ended September 30, 2023, less than 1 thousand shares and 64 thousand shares, respectively, of Adtran Networks stock was tendered to the Company and Exit Compensation payments of approximately € 8 thousand and € 1.1 million, respectively, or approximately $ 9 thousand and $ 1.2 million, respectively, based on an exchange rate as of September 30, 2023, were paid to Adtran Networks shareholders. As of September 30, 2023, and as of the date of issuance of these financial statements, the Company does not have sufficient liquidity to meet payment obligations under the DPLTA pertaining to Exit Compensation assuming a substantial majority of Adtran Networks shareholders elect such option in the current period. We believe the probability that a substantial majority of Adtran Networks shareholders elect to receive Exit Compensation in the next twelve months is remote based on the diverse base of shareholders that must make this election on an individual shareholder basis, the current ongoing appraisal proceedings involving a dispute on the value of the Exit Compensation which is expected to take 24-36 months to resolve, the current guaranteed Annual Recurring Compensation payment plus the interest earned on such shares during the ongoing appraisal proceedings, and the current trading value of Adtran Networks SE shares. Therefore, we believe that our cash and cash equivalents, investments, working capital management initiatives and access to funds under the Wells Fargo credit facility, including additional funding provided for under the First Amendment to the Wells Fargo credit facility that was signed on August 9, 2023, (described below) will be adequate to meet our operating and capital needs and our obligations under the DPLTA, including potential Exit Compensation, for at least the next 12 months, from the issuance of these financial statements, although we have suspended dividend payments and are implementing a business efficiency program, which includes, but is not limited to, planned reductions in our operating expenses and a site consolidation plan. In connection with the site consolidation plan, we are also exploring a potential sale of our headquarters in Huntsville. We may also need to further reduce capital expenditures and/or take other steps to preserve working capital in order to ensure that we can meet such needs and obligations. See Note 22, Subsequent Events, for additional information regarding the suspension of the quarterly dividend. 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 allowed for borrowings of up to $ 100.0 million in aggregate principal amount, but the borrowings increased to up to $ 400.0 million in aggregate principal amount upon the DPLTA becoming effective on January 16, 2023. On August 9, 2023, the Company, its wholly-owned direct subsidiary, ADTRAN, Inc., the lenders party thereto and the Administrative Agent entered into a First Amendment to the Credit Agreement (the “First Amendment” and, together with the Credit Agreement, the “Credit Facility”). The Credit Facility matures in July 2027; however, the Company has an option to request extensions subject to customary conditions. See Note 12, Revolving Credit Agreements, for additional information regarding the terms of the Credit Facility. 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. The December 31, 2022 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 Amendment No. 1 to the ADTRAN Holdings, Inc. Annual Report on Form 10-K for the year ended December 31, 2022 , filed with the SEC on August 14, 2023. 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, estimates of intangible assets upon measurement, estimated pension liability and fair value of investments and estimated contingent liabilities. 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 supply chain constraints, inflationary pressures, the energy crisis, currency fluctuations and political tensions as of September 30, 2023, 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 as sets, revenue recognition and costs of revenue. Future conditions related to supply chain constraints, inflationary pressures, the energy crisis, rising interest rates, instability in the financial services industry, currency fluctuations and political tensions could result in further impacts to the Company's consolidated financial statements in future reporting periods . Redeemable Non-Controlling Interest As of September 30, 2023 and December 31, 2022, the non-controlling Adtran Networks stockholders’ equity ownership percentage in Adtran Networks was approximately 34.6 % and 34.7 %, respectively. As a result of the effectiveness of the DPLTA on January 16, 2023, the Adtran Networks shares, representing the equity interest in Adtran Networks held by holders other than the Company, can be tendered at any time and are, therefore, redeemable and must be classified outside stockholders’ equity. Therefore, the permanent equity noncontrolling interest balance was reclassified to redeemable non-controlling interest on January 16, 2023 and was remeasured to fair value based on the trading market price of the Adtran Networks shares. Subsequently, the carrying value of the RNCI is adjusted to its maximum redemption value at each reporting date when the maximum redemption value is greater than the initial carrying amount of the RNCI. However, the RNCI will be remeasured using the current exchange rate at each reporting date as long as the RNCI is currently redeemable. For the period of time that the DPLTA is in effect, the RNCI will continue to be presented as RNCI outside of stockholders’ equity in the Condensed Consolidated Balance Sheets. See Note 16 for additional information on RNCI . 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. Recent Accounting Pronouncements Not Yet Adopted There are currently no accounting pronouncements not yet adopted that are expected to have a material effect on the Condensed Consolidated Financial Statements.

Business Combination

Business Combination	9 Months Ended
	Sep. 30, 2023
Business Combinations [Abstract]
Business Combination	2. BUSINESS COMBINATION Adtran Networks SE (formerly ADVA Optical Networking SE) On August 30, 2021 , ADTRAN, Inc. and Adtran Networks (then known as ADVA Optical Networking SE) 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, Inc. 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, Inc., with ADTRAN, Inc. surviving the Business Combination as a wholly-owned direct subsidiary of the Company. Additionally, pursuant to the Business Combination Agreement, on July 15, 2022, the Compa ny made a public offer to exchange each issued and outstanding no-par value bearer share of Adtran Networks for 0.8244 shares of Company Common Stock, par value $ 0.01 per share of the Company. The Exchange Offer was settled on July 15, 2022 (the "Exchange Offer Settlement Date"), on which date the Company acquired 33,957,538 bearer shares of Adtran Networks, or 65.43 % of Adtran Networks’ 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, Adtran Networks stock option holders were entitled to have their Adtran Networks 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 fair value of the Adtran Networks stock options assumed by ADTRAN Holdings, Inc. was $ 12.8 million, estimated using the Monte Carlo method. ADTRAN, Inc. and Adtran Networks became subsidiaries of ADTRAN Holdings, Inc. as a result of the Business Combination. ADTRAN, Inc. was determined to be the accounting acquirer of Adtran Networks based on ADTRAN, Inc. 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 with Adtran Networks 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 Adtran Networks shares of common stock, which resulted in a 36.0 % equity stake for Adtran Networks stockholders and a 64.0 % equity stake for ADTRAN, Inc. stockholders in the post-closing combined company (calculated on a fully diluted basis and utilizing the tender of 65.43 % of Adtran Networks’ current issued and outstanding share capital) as of July 15, 2022. Therefore, ADTRAN, Inc. shareholders continued to hold a majority interest in the combined company following the completion of the Business Combination. Additionally, following the transaction, the Board of Directors was comprised of six members from ADTRAN, Inc. and three members from Adtran Networks; the ADTRAN, Inc. chief executive officer became and continues to act as the chairman of the Board of Directors and the former Adtran Networks chief executive officer became the vice chairman of the Board of Directors. Additionally, the ADTRAN, Inc. chief executive officer and ADTRAN, Inc. chief financial officer held these positions within the combined company immediately following the completion of the Business Combination. Based upon these and other considerations as outlined in ASC 805, ADTRAN, Inc. represented the accounting acquirer. The following table summarizes the purchase price for the Adtran Networks business combination: (In thousands, except shares, share price and exchange ratio) Purchase Price Adtran Networks 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 Adtran Networks 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. In determining the fair value, the Company utilized various methods of the income, cost and market approaches depending on the asset or liability being fair valued. The estimation of fair value required significant judgment related to future net cash flows reflecting the risk inherent in each cash flow stream, competitive trends, market comparables and other factors. Inputs were generally determined by taking into account historical data, current and anticipated market conditions, and growth rates. Developed technology and customer relationships were valued using the multi-period excess earnings method. Backlog was valued using the distributor method. Significant assumptions used in the discounted cash flow analysis for (i) developed technology were the revenue growth rates, long-term revenue growth rate, discount rate, and earnings before interest, taxes, depreciation and amortization (“EBITDA”) margins, obsolescence factors, income tax rate, tax depreciation, and economic depreciation; (ii) customer relationships were earnings before interest and taxes (“EBIT”) margins, contributory asset charges, and customer attrition rate; and (iii) backlog were EBIT margins, adjusted EBIT margins, and contributory asset charges. The allocation of the purchase price to the assets acquired and liabilities assumed was subject to adjustment within the measurement period (up to one year from the acquisition date). The measurement period adjustments since initial preliminary estimates resulted from changes to the fair value estimates of the acquired assets and assumed liabilities based on finalizing the valuations of inventory, prepaid expenses and other current assets, property plant and equipment, intangible assets, other non-current assets and deferred tax assets and liabilities. The cumulative effect of all measurement period adjustments resulted in a decrease to recognized goodwill of $ 8.7 million. The following table summarizes the final purchase price allocation for each major class of assets acquired and liabilities assumed in the Business Combination (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 200,331 Prepaid expenses and other current assets 28,208 Property plant and equipment 55,480 Deferred tax assets 1,759 Intangibles 403,780 Other non-current assets 31,074 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, net ( 4,898 ) Tax liabilities ( 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 ( 61,040 ) Total net assets acquired $ 544,217 Goodwill $ 350,458 The fair value of the assets acquired included accounts receivable of $ 114.7 million and other receivables of $ 1.5 million. The unpaid principal balance under these receivables was $ 118.5 million and $ 1.5 million, respectively. The difference between the fair value and the unpaid principal balance primarily represents amounts determined to be uncollectible. The fair value of the identifiable 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 $ 291,925 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 $ 403,780 (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. The Business Combination resulted in the recognition of goodwill of $ 350.5 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 Business Combination 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. The goodwill resulting from the Business Combination of $ 272.8 million was allocated to the Network Solutions segment, and $ 77.7 million was allocated to the Services & Support segment. See Note 18 of the Notes to Consolidated Financial Statements, included in 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 Adtran Networks' shares remains trading after the Business Combination, the non-controlling interest was calculated using 17,941,496 Adtran Networks shares held by non-controlling interest multiplied by the Adtran Networks 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 has included the financial results of Adtran Networks in its consolidated financial statements since July 15, 2022, the acquisition date. The net revenue from the Adtran Networks business for the three and nine months ended September 30, 2023, was $ 158.4 million and $ 537.5 million, respectively, and the net loss from the Adtran Networks business for the three and nine months ended September 30, 2023, was $ 38.8 million and $ 79.4 million, respectively, which are included in the Company’s Consolidated Statement of Loss. There was no net loss attributable to non-controlling interest from the Adtran Networks business for the three months ended September 30, 2023. The net loss attributable to non-controlling interest from the Adtran Networks business for the nine months ended September 30, 2023 was $ 3.2 million. For the three and nine months ended September 30, 2023 , we recognized $ 2.9 million and $ 8.6 million, respectively, representing the portion of the annual recurring cash compensation to the non-controlling shareholders accrued during such periods, which will be paid after the ordinary general shareholders' meeting of Adtran Networks beginning in 2024. See Note 1 and Note 20 for additional information on RNCI and the annual dividend . As of September 30, 2023, the Company has incurred $ 26.2 million of transaction costs related to the Business Combination. During the three and nine months ended September 30, 2023, $ 8 thousand and $ 0.1 million of transaction costs were incurred, respectively. During the three and nine months ended September 30, 2022, $ 10.6 million and $ 13.3 million of transaction costs were incurred, respectively. These transaction costs are recorded in selling, general and administrative expenses in the 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, Inc. and Adtran Networks as though the Business Combination had occurred on January 1, 2022. 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, 2022, 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 that the Company has incurred and may continue to incur related to the Business Combination as part of combining the operations of the companies. Three Months Ended Nine Months Ended (In thousands) September 30, 2022 September 30, 2022 Revenue $ 368,192 $ 1,053,510 Net loss $ ( 48,084 ) $ ( 60,494 )

Revenue

Revenue	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenue	3. 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 which support the Company's Subscriber, Access & Aggregation, and Optical Networking Solutions. Services & Support Segment - Includes network design, implementation, maintenance and cloud-hosted services supporting the Company's Subscriber, Access & 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 Adtran Networks 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 Adtran Networks, we have recast these revenues such that ADTRAN’s former Access & Aggregation revenue is combined with a portion of the applicable Adtran Networks SE solutions to create Access & Aggregation Solutions; ADTRAN’s former Subscriber Solutions & Experience revenue is combined with a portion of the applicable Adtran Networks 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 Adtran Networks' 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, 2023 September 30, 2022 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Optical Networking Solutions $ 94,592 $ 21,608 $ 116,200 $ 103,011 $ 15,834 $ 118,845 Access & Aggregation Solutions 81,051 13,595 94,646 76,591 11,598 88,189 Subscriber Solutions 52,921 8,564 61,485 125,338 8,337 133,675 Total $ 228,564 $ 43,767 $ 272,331 $ 304,940 $ 35,769 $ 340,709 Nine Months Ended September 30, 2023 September 30, 2022 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Optical Networking Solutions $ 342,390 $ 64,562 $ 406,952 $ 103,011 $ 15,834 $ 118,845 Access & Aggregation Solutions 254,868 39,315 294,183 243,396 34,877 278,273 Subscriber Solutions 196,726 25,760 222,486 252,899 17,248 270,147 Total $ 793,984 $ 129,637 $ 923,621 $ 599,306 $ 67,959 $ 667,265 The aggregate amount of transaction price allocated to remaining performance obligations that have not been satisfied as of September 30, 2023 and December 31, 2022 related to contractual maintenance agreements, contractual SaaS and subscription services, and hardware contracts that exceed one year in duration amounted to $ 314.0 milli on and $ 277.2 million, respectively. As of September 30, 2023, approximately 68.6 % is expected to be recognized over the next 12 months and the remainder recognized thereafter. The majority of the Company's remaining performance obligations as of September 30, 2023 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, 2023 December 31, 2022 Accounts receivable, net $ 229,333 $ 279,435 Contract assets (1) $ 888 $ 1,852 Unearned revenue $ 49,832 $ 41,193 Non-current unearned revenue $ 23,501 $ 19,239 (1) Included in other receivables on the Condensed Consolidated Balance Sheets. The Company is party to a receivables purchase agreement with a third-party financial institution (the “Factor”), which accelerates receivable collection and helps to better manage cash flow. Total accounts receivables sold for the nine months ended September 30, 2023 and the twelve months ended December 31, 2022, totaled $ 17.8 million and $ 14.9 million, respectively, of which $ 1.4 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, 2023 and December 31, 2022, the Company had an allowance for credit losses related to factored accounts receivable totaling less than $ 0.1 million. The cost of the receivables purchase agreement is included in interest expense in the Condensed Consolidated Statements of Loss and totaled $ 0.3 million and $ 0.9 million for the three and nine months ended September 30, 2023, respectively. Of the outstanding unearned revenue balances as of December 31, 2022, $ 6.1 million and $ 31.3 milli on were recognized as revenue during the three and nine months ended September 30, 2023, respectively . Of the $ 17.7 million of outstanding unearned revenue balances as of December 31, 2021, $ 2.8 million and $ 12.3 million were recognized as revenue during the three and nine months ended September 30, 2022, 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, 2023 and December 31, 2022 , the Company’s outstanding accounts receivable balance was $ 229.3 million and $ 279.4 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 $ 15 thousand and $ 49 thousand as of September 30, 2023 and December 31, 2022, respectively, 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, 2023 and December 31, 2022 , the Company’s outstanding contract asset balance was $ 0.9 million and $ 1.9 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 three months ended September 30, 2023 and 2022 related to contract assets.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	4. INCOME TAXES The Company’s effective tax rate changed from a benefit of 8.8 % of pre-tax loss for the three months ended September 30, 2022 , to a benefit of 18.0 % of pre-tax loss for the three months ended September 30, 2023 and changed from a benefit of 9.4 % of pre-tax loss for the nine months ended September 30, 2022 , to a benefit of 19.2 % of pre-tax loss for the nine months ended September 30, 2023. The change in the effective tax rate for the three and nine months ended September 30, 2023, was driven primarily by a change in our estimated tax rate as a result of the closing of the Business Combination with Adtran Networks during the third quarter of 2022, as well as the release of our domestic valuation allowance during the fourth quarter of 2022, with exception for certain research and development credits in a particular state in which we do not have sufficient activity to utilize them prior to expiration. During the second quarter of 2023, the Company concluded a review with the Internal Revenue Services of its amended tax returns previously filed related to refund claims arising from the Company’s request to revoke an IRC Section 59(e) election made on the Company’s originally filed 2018 U.S. federal tax return. The Company had previously received an unfavorable response to its Private Letter Ruling request, in which it requested the Commissioner's approval for revoking the election. As a result of that review, and after taking into consideration other factors, including weighing the potential benefits with projected costs to litigate and the hazards of litigation, management has concluded that it will not pursue the claims any further. As a result, the Company has removed the previously recorded receivable of $ 15.2 million and related research and development credit carryforward of $ 1.8 million, as well as the offsetting uncertain tax position reserves against them of $ 17.0 million during the second quarter of 2023. 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, 2023 , the Company had net deferred tax assets totaling $ 57.3 million, and a valuation allowance totaling $ 5.0 million against those deferred tax assets. The remaining $ 52.3 million in deferred tax assets are primarily related to capitalized R&D expenses in the U.S., partially offset by net purchase price intangibles from the Business Combination closed with Adtran Networks during the third quarter of 2022. 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, 2023 (In thousands) Deferred Tax Assets (Liabilities) Valuation Allowance Deferred Tax Assets (Liabilities), net Domestic $ 84,274 $ ( 3,177 ) $ 81,097 International ( 26,975 ) ( 1,839 ) ( 28,814 ) Total $ 57,299 $ ( 5,016 ) $ 52,283 As of December 31, 2022 (In thousands) Deferred Tax Assets (Liabilities) Valuation Allowance Deferred Tax Assets (Liabilities), net Domestic $ 61,726 $ ( 3,177 ) $ 58,549 International ( 50,315 ) ( 2,024 ) ( 52,339 ) Total $ 11,411 $ ( 5,201 ) $ 6,210

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	5. STOCK-BASED COMPENSATION For the three months ended September 30, 2023 and 2022 , stock-based compensation expense was $ 4.2 million and $ 12.1 million, respectively, and for the nine months ended September 30, 2023 and 2022 , stock-based compensation expense was $ 12.2 million and $ 15.9 million, respectively. PSUs, RSUs and Restricted Stock - ADTRAN Holdings, Inc. The following table summarizes the RSUs and restricted stock outstanding as of December 31, 2022 and September 30, 2023 and the changes that occurred during the nine months ended September 30, 2023: Number of Weighted Avg. Grant Date Fair Value Unvested RSUs and restricted stock outstanding, December 31, 2022 1,086 $ 17.54 RSUs and restricted stock granted 1,484 $ 16.58 RSUs and restricted stock vested ( 56 ) $ 20.37 RSUs and restricted stock forfeited ( 51 ) $ 16.42 Unvested RSUs and restricted stock outstanding, September 30, 2023 2,463 $ 17.01 During the nine months ended September 30, 2023, the Company granted 0.9 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 either a two or three-year period, subject to the gra ntee’s continued employment, with the ability to earn shares in a range of 0 % to either 100 % or 150 % of the awarded number of PSUs based on the achievement of defined performance targets. Equity-based compensation expense and liabilities 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. 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, 2023 , total unrecognized compensation expense related to non-vested market-based RSUs and restricted stock was approximately $ 19.1 million, which will be recognized over the remaining weighted-average period of 2.2 years. There was $ 11.3 million of unrecognized compensation expense related to unvested 2023 performance-based PSUs, which will be recognized over the remaining requisite service period of 2.3 years if achievement of the performance obligation becomes probable. Unrecognized compensation expense will be adjusted for actual forfeitures. As of September 30, 2023, 2.0 million shares were available for issuance under stockholder-approved equity plans. Stock Options - ADTRAN Holdings, Inc. The following table summarizes the ADTRAN Holdings, Inc. stock options outstanding as of December 31, 2022 and September 30, 2023 and the changes that occurred during the nine months ended September 30, 2023: Number of Weighted Avg. Weighted Avg. Aggregate Stock options outstanding, December 31, 2022 3,148 $ 14.37 3.42 $ 16,251 Stock options granted 7 $ 12.17 Stock options exercised ( 8 ) $ 8.72 Stock options forfeited ( 40 ) $ 11.93 Stock options expired ( 33 ) $ 16.44 Stock options outstanding, September 30, 2023 3,074 $ 14.39 2.68 $ 736 Stock options exercisable, September 30, 2023 1,691 $ 15.88 1.23 $ 556 As of September 30, 2023 , there was $ 5.2 million of unrecognized compensation expense related to stock options which will be recognized over the remaining weighted-average period of 1.9 years. Pursuant to the Business Combination, which closed on July 15, 2022, Adtran Networks stock option holders were entitled to have their Adtran Networks 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 maximum number of shares of ADTRAN Holdings, Inc. stock potentially issuable upon such assumption was 2.3 million shares. The period in which such options could be assumed ended on July 22, 2022. A total of 2.1 million shares of ADTRAN Holdings, Inc. stock could be issued pursuant to the exercise of the assumed Adtran Networks options. The determination of the fair value of stock options assumed by ADTRAN Holdings, Inc. 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 the Company'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, 2023 . The amount of aggregate intrinsic value was $ 0.7 million as of September 30, 2023, which will change based on the fair market value of the Company's stock. The total pre-tax intrinsic value of options exercised during the nine months ended September 30, 2023 was $ 50 thousand. Stock Options - Adtran Networks The following table summarizes the Adtran Networks stock options outstanding as of December 31, 2022 and September 30, 2023 and the changes that occurred during the nine months ended September 30, 2023: Number of (In thousands) Weighted (Per share) Weighted Avg. Aggregate Value (In thousands) Stock options outstanding, December 31, 2022 81 $ 8.58 4.00 $ 1,222 Stock options exercised ( 13 ) $ 8.22 Stock options forfeited ( 9 ) $ 10.58 Stock options expired ( 1 ) $ 9.20 Stock options outstanding, September 30, 2023 58 $ 8.18 3.39 $ 746 Stock options exercisable, September 30, 2023 12 $ 6.03 1.48 $ 182 As of September 30, 2023 , there was $ 0.1 million of unrecognized compensation expense related to Adtran Networks stock options which will be recognized over the remaining weighted-average period of 3.4 years. All of the Adtran Networks options were previously issued at exercise prices that approximated fair market value at the date of grant. The aggregate intrinsic value of Adtran Networks stock options represents the total pre-tax intrinsic value (the difference between Adtran Networks 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, 2023 . The amount of aggregate intrinsic value was $ 0.7 million as of September 30, 2023 and will change based on the fair market value of Adtran Networks stock. The total pre-tax intrinsic value of Adtran Networks options exercised during the nine months ended September 30, 2023 was $ 0.2 million.

Investments

Investments	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Investments	6. 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 December 31, 2022: As of December 31, 2022 Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 2,538 $ 5 $ ( 81 ) $ 2,462 Municipal fixed-rate bonds 185 — ( 5 ) 180 Asset-backed bonds 818 1 ( 24 ) 795 Mortgage/Agency-backed bonds 1,853 — ( 105 ) 1,748 U.S. government bonds 3,870 3 ( 188 ) 3,685 Foreign government bonds 407 — ( 24 ) 383 Available-for-sale debt securities held at fair value $ 9,671 $ 9 $ ( 427 ) $ 9,253 The Company did no t have any debt securities and other investments as of September 30, 2023. Re alized 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) 2023 2022 2023 2022 Gross realized gain on debt securities $ 5 $ 1 $ 9 $ 14 Gross realized loss on debt securities ( 317 ) ( 116 ) ( 355 ) ( 242 ) Total loss recognized, net $ ( 312 ) $ ( 115 ) $ ( 346 ) $ ( 228 ) 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, 2023 and 2022 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 5.0 % 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, 2023. 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) 2023 2022 2023 2022 Unrealized gain (loss) on equity securities held $ ( 1,130 ) $ ( 1,217 ) $ 1,404 $ ( 8,849 ) Realized gain (loss) on equity securities sold ( 1 ) ( 1,358 ) 13 ( 1,675 ) Total gain (loss) recognized, net $ ( 1,131 ) $ ( 2,575 ) $ 1,417 $ ( 10,524 ) 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, 2023 Using (In thousands) Fair Value Quoted Prices Significant Significant Unobservable Inputs Cash equivalents U.S. government securities $ — $ — $ — $ — Money market funds 5,245 5,245 — — Commercial paper — — — — Total cash equivalents $ 5,245 $ 5,245 $ - $ — Marketable equity securities Marketable equity securities – various industries 815 815 — — Deferred compensation plan assets 24,364 24,364 — — Total long-term investments $ 25,179 $ 25,179 $ — $ — Total $ 30,424 $ 30,424 $ — $ — Fair Value Measurements as of December 31, 2022 Using (In thousands) Fair Value Quoted Prices Significant Significant Unobservable Inputs Cash equivalents Money market funds $ 228 $ 228 $ — $ — Total cash equivalents $ 228 $ 228 $ — $ — Available-for-sale debt securities Corporate bonds $ 2,462 $ — $ 2,462 $ — Municipal fixed-rate bonds 180 — 180 — Asset-backed bonds 795 — 795 — Mortgage/Agency-backed bonds 1,748 — 1,748 — U.S. government bonds 3,685 3,685 — — Foreign government bonds 383 — 383 — Marketable equity securities Marketable equity securities – various industries 810 810 — — Deferred compensation plan assets 22,942 22,942 — — Total short-term and long-term investments $ 33,005 $ 27,437 $ 5,568 $ - Total $ 33,233 $ 27,665 $ 5,568 $ — 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, 2023
Inventory Disclosure [Abstract]
Inventory	7. INVENTORY Inventory consisted of the following: As of As of (In thousands) September 30, 2023 December 31, 2022 Raw materials $ 156,287 $ 186,346 Work in process 15,648 12,087 Finished goods 202,036 229,098 Total inventory, net $ 373,971 $ 427,531 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, 2023 and December 31, 2022, inventory reserves were $ 86.3 million and $ 57.0 million, respectively. In connection with the Company’s restructuring efforts, during the quarter ended September 30, 2023, management determined that there would be a discontinuation of product lines in the Network solutions segment and, as a result, wrote-down related inventories of $ 21.0 million and is included in cost of revenue in the Condensed Consolidated Statements of Loss. There was no write-down of inventory during the three and nine months ended September 30, 2022.

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	8. PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment consisted of the following: As of As of (In thousands) September 30, 2023 December 31, 2022 Engineering and other equipment $ 179,049 $ 170,785 Building 85,966 82,932 Computer hardware and software 97,192 80,455 Building and land improvements 51,284 47,861 Furniture and fixtures 23,686 22,403 Land 5,325 5,364 Total property, plant and equipment 442,502 409,800 Less: accumulated depreciation ( 323,879 ) ( 299,101 ) Total property, plant and equipment, net $ 118,623 $ 110,699 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. During the three and nine months ended September 30, 2023, no impairment charges were recognized. Depreciation expense was $ 7.4 million and $ 7.1 million for the three months ended September 30, 2023 and 2022 , respectively, and $ 22.6 million and $ 12.6 million for the nine months ended September 30, 2023 and 2022 , 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, 2023
Goodwill Disclosure [Abstract]
Goodwill	9. GOODWILL The changes in the carrying amount of goodwill for the nine months ended September 30, 2023 are as follows: (In thousands) Network Solutions Services & Support Total As of December 31, 2022 $ 298,280 $ 83,444 $ 381,724 Goodwill impairment — ( 37,500 ) ( 37,500 ) Foreign currency translation adjustments ( 3,873 ) ( 1,268 ) ( 5,141 ) As of September 30, 2023 $ 294,407 $ 44,676 $ 339,083 Related to the Business Combination with Adtran Networks, the Company recognized $ 350.5 million of goodwill upon the closing of the Business Combination on July 15, 2022. Goodwill represents the excess purchase price over the fair value of net assets acquired. The Company performed an impairment assessment as of September 30, 2023, prior to our October 1, 2023 annual measurement date. The Company’s policy is to assess the realizability of its goodwill, and to evaluate such assets for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets (or group of assets) may not be recoverable. During the third quarter of 2023, qualitative factors such as a decrease in the Company's market capitalization and long-term projections, triggered a quantitative impairment assessment for our reporting units. The Company determined the fair value of each reporting unit using a combination of an income approach and a market based peer group analysis. It was determined that the decreases in projected future cash flows, discount rates, overall macroeconomic conditions, as well as the decrease in our market capitalization applied in the valuation, were required to align with market-based assumptions and company-specific risk, which resulted in lower fair values of the Services & Support reporting unit. The Company determined upon its quantitative impairment assessment to recognize a $ 37.9 million non-cash goodwill impairment charge for the Services & Support reporting unit. The Company does not expect the impairment charge for the Services & Support Unit to result in any future cash expenditures. The Company did not recognize any impairment charges for the Network Solutions reporting unit as of September 30, 2023. Subsequent to September 30, 2023, the Company has experienced volatility in its stock price which reduced the market value of the Company’s common stock as of this filing. The Company will continue to monitor its stock price, operating results and other macroeconomic factors to determine if there is further indication of a sustained decline in fair value requiring an event driven assessment of the recoverability of its goodwill within the fourth quarter of 2023.

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2023
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	10. INTANGIBLE ASSETS Intangible assets consisted of the following: As of September 30, 2023 As of December 31, 2022 (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 $ 53,247 $ ( 14,490 ) $ 38,757 $ 55,517 $ ( 12,772 ) $ 42,745 Backlog 1.6 55,017 ( 49,061 ) 5,956 55,782 ( 22,725 ) 33,057 Developed technology 8.5 316,083 ( 49,944 ) 266,139 320,364 ( 21,856 ) 298,508 Licensed technology 9.0 5,900 ( 3,633 ) 2,267 5,900 ( 3,141 ) 2,759 Licensing agreements 8.5 560 ( 353 ) 207 560 ( 298 ) 262 Patents 7.3 500 ( 483 ) 17 500 ( 431 ) 69 Trade names 3.0 28,461 ( 13,109 ) 15,352 29,066 ( 5,255 ) 23,811 Total $ 459,768 $ ( 131,073 ) $ 328,695 $ 467,689 $ ( 66,478 ) $ 401,211 Intangible assets are reviewed for impairment whenever events and circumstances indicate impairment may have occurred. The Company assessed impairment triggers related to intangible assets during each financial period in 2023 and 2022. During the third quarter of 2023, the Company's market capitalization and long-term projections decreased which triggered a reassessment of our estimated future undiscounted cash flows. The Company determined that our estimated future undiscounted cash flows exceeded the carrying amount of intangible assets as of September 30, 2023. No quantitative impairment test of long-lived assets was performed as of September 30, 2022. No impairment losses of intangible assets were recorded during the three and nine months ended September 30, 2023 and 2022. Amortization expense was $ 16.5 million and $ 20.4 million in the three months ended September 30, 2023 and 2022 , respectively, and $ 68.8 million and $ 22.2 million in the nine months ended September 30, 2023 and 2022, 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 is as follows: As of (In thousands) September 30, 2023 2023 $ 13,770 2024 56,800 2025 45,504 2026 42,290 2027 40,941 Thereafter 129,390 Total $ 328,695

Hedging

Hedging	9 Months Ended
	Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Hedging	11. HEDGING The Company has certain forward rate agreements to hedge foreign currency exposure of expected future cash flows in foreign currency. The Company does not hold or issue derivative instruments for trading or other speculative purposes. Derivatives are initially recognized at fair value on the date a derivative contract is entered into and are subsequently re-measured to their fair value at the end of each reporting period. All changes in the fair value of derivative instruments are recognized as other income (expense) in the Consolidated Statements of Loss and are classified as Level II under the fair value hierarchy. The derivative instruments are not subject to master netting agreements and are not offset in the Consolidated Balance Sheets. We are exposed to risk from credit-related losses resulting from nonperformance by counterparties to our financial instruments. We perform credit evaluations of our counterparties under forward exchange contracts and expect all counter parties to meet their obligations. We have not experienced credit losses from our counterparties. As of September 30, 2023, the Company had 49 fo rward rate contracts outstanding. Foreign Currency Hedging Arrangements On November 3, 2022, the Company entered into a Euro/U.S. forward contract arrangement (the “Initial Forward”) with Wells Fargo Bank, N.A. (the “Hedge Counterparty”). The Initial Forward, 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, enables the Company to conv ert a portion of its Euro denominated payment obligations under the DPLTA into U.S. Dollars. Under the Initial Forward, the Company agreed to exchange an aggregate notional amount of € 160.0 million for U.S. dollars at a daily fixed forward rate ranging from $ 0.98286 to $ 1.03290 . The aggregate amount of € 160.0 million is divided into eight quarterly tranches of € 20.0 million, which commenced in the fourth quarter of 2022. During the nine months ended September 30, 2023, the Company se ttled three € 20.0 million forward contract tranches a nd the remaining amount will be divided into five 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 Initial Forward 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. On March 21, 2023, the Company entered into a Euro/U.S. dollar forward contract arrangement (the “Forward”) with the Hedge Counterparty. Under the Forward, which is governed by the provisions of an ISDA Master Agreement (including schedules thereto and transaction confirmations that supplemen t such agreement) entered into between the Company and the Hedge Counterparty, the Company will exchange an aggregate notional amount of € 160.0 million for U.S. dollars at a daily fixed forward rate of $ 1.085 per € 1.00 in average. During the nine months ended September 30, 2023, the Company se ttled three € 20.0 million forward contract tranches, a nd the remaining amount will be divided into five quarterly tranches of € 20.0 million. These forward contracts were executed on March 21, 2023 (to sell EUR/buy USD) and were entered into for the purpose of unwinding the Initial Forward (to buy EUR/sell USD). The drawdown dates of the Initial Forward are set to the same date as the maturity of the new offsetting Forward. The fair values of the Company's derivative instruments recorded in the Condensed Consolidated Balance Sheet as of September 30, 2023 and December 31, 2022 were as follows: (In thousands) Balance Sheet Location September 30, 2023 December 31, 2022 Derivatives Not Designated as Hedging Instruments (Level 2): Foreign exchange contracts – derivative assets Other receivables $ 7,530 $ 11,992 Foreign exchange contracts – derivative liabilities Accounts payable $ ( 10 ) $ ( 633 ) Total derivatives $ 7,520 $ 11,359 The change in the fair values of the Company's derivative instruments recorded in the Condensed Consolidated Statements of Loss during the three and nine months ended September 30, 2023 and 2022 were as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) Income Statement 2023 2022 2023 2022 Derivatives Not Designated as Hedging Instruments: Foreign exchange contracts Other income, net $ 1,012 $ — $ 1,076 $ —

Revolving Credit Agreements

Revolving Credit Agreements	9 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Revolving Credit Agreements	12. REVOLVING CREDIT AGREEMENTS The carrying amounts of the Company's current and non-current revolving credit agreements in its Condensed Consolidated Balance Sheets were as follows: As of As of (In thousands) September 30, 2023 December 31, 2022 New Nord/LB revolving line of credit $ 10,580 $ — Nord/LB revolving line of credit — 16,091 Syndicated credit agreement working capital line of credit — 10,727 DZ bank revolving line of credit — 9,118 Total current revolving credit agreements $ 10,580 $ 35,936 As of As of (In thousands) September 30, 2023 December 31, 2022 Wells Fargo credit agreement $ 200,000 $ 60,000 Total non-current revolving credit agreement $ 200,000 $ 60,000 As of September 30, 2023 , the weighted average interest rate on our revolving credit agreements was 7.11 %. 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 initially allowed for borrowings of up to $ 100.0 million in aggregate principal amount, but the permitted borrowings increased to up to $ 400.0 million in aggregate principal amount upon the DPLTA becoming effective on January 16, 2023. On August 9, 2023, (the "First Amendment Effective Date") the Company, its wholly-owned direct subsidiary, ADTRAN, Inc., the lenders party thereto and the Administrative Agent entered into a First Amendment to the Credit Agreement (the “First Amendment” and together with the Credit Agreement, the "Credit Facility"). The First Amendment, provides for, among other things, a new $ 50.0 million delayed draw term loan (“DDTL”), which is available for borrowing in the event of the purchase by the Company of at least sixty percent ( 60.0 %) of the outstanding shares of Adtran Networks that were not owned by the Company as of the First Amendment Effective Date (such event, a “Springing Covenant Event”). Proceeds of the DDTL may only be used to repurchase minority shares of Adtran Networks. The DDTL remains available for borrowing from the occurrence of a Springing Covenant Event through the period that is three consecutive fiscal quarters thereafter. The First Amendment further added additional financial flexibility by amending the $ 30.0 million external debt capped basket to be an unlimited amount and permitting, subject to certain requirements, the incurrence of convertible indebtedness by the Company in an aggregate principal amount of up to $ 172.5 million. Any such convertible indebtedness must be incurred in pro forma compliance with the financial covenants in the Credit Agreement, unsecured and otherwise rank junior to borrowings under the Credit Agreement, and have a stated maturity date of at least 91 days after the latest scheduled maturity date of loans and commitments under the Credit Agreement. Net cash proceeds from any incurrence of convertible indebtedness must be used to repurchase minority shares of Adtran Networks or repay revolver borrowings under the Credit Agreement. As of September 30, 2023 , ADTRAN, Inc.’s borrowings under the revolving line of credit were $ 200.0 million. As of September 30, 2023, there were no borrowings under the DDTL. The Credit Facility matures in July 2027; however, the Company has an option to request extensions subject to customary conditions. In addition, we may issue up to $ 25.0 million in letters of credit against our $ 400.0 million total facility. As of September 30, 2023 , we had a total of $ 2.2 million in letters of credit under ADTRAN, Inc. outstanding against our eligible borrowings, leaving a net amount of $ 197.8 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. Revolving Line of Credit Interest Rate All U.S. borrowings under the revolving line of credit (other than swingline loans, which bear interest at the Base Rate (as defined below)) 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 1.0 %, (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 1.0 %, plus (ii) the applicable rate, ranging from 0.65 % to 1.65 % (the “Base Rate”), or (B) the sum of the Adjusted Term SOFR (as defined in the Credit Agreement) plus the applicable rate, ranging from 1.65 % to 2.65 %, 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) 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 1.75 % to 2.75 %, 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 2.0 % 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 ranging from 0.20 % to 0.25 % per annum on the average daily unused portion of the revolving credit commitment 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 participation in letters of credit at the then applicable rate for SOFR Loans. DDTL Interest Rate All U.S. borrowings under the DDTL 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 1.0 %, (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 sum of the Adjusted Term SOFR (as defined in the Credit Agreement) plus the applicable rate, ranging from 1.9 % to 2.9 %, provided that such sum is subject to a 0.0 % floor (such loans utilizing this interest rate, “SOFR Loans”) or (B) the sum of the daily Adjusted Term SOFR (as defined in the Credit Agreement) for a one-month tenor plus 1.0 %, plus (ii) the applicable rate, ranging from 0.9 % to 1.9 %. 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 2.0 % 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 DDTL loan, the Company is required to pay a commitment fee to the lenders under the Credit Agreement in respect of unutilized DDTL commitments at a rate of 0.25 % per annum on the daily unused portion of the aggregate DDTL commitment until the earliest of (i) the delayed draw funding date, (ii) the delayed draw funding deadline and (iii) the termination in full of the DDTL commitments. Covenants Under the Credit Agreement The First Amendment permits the Company to prepay any or all of the outstanding loans or to reduce the commitments under the First Amendment without incurring premiums or penalties (except breakage costs with respect to SOFR Loans and EURIBOR Loans). The First Amendment 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). The First Amendment further included the following revised financial covenants; (i) the addition of an automatic step up in the consolidated total net leverage ratio to 5.00 :1.00 from 3.25 :1.00 upon the occurrence of a Springing Covenant Event and continuing for the fiscal quarter in which the Springing Covenant Event occurs and the next three consecutive fiscal quarters thereafter (such period, a “Springing Covenant Period”) and (ii) the addition of a consolidated senior secured net leverage ratio covenant to be tested quarterly during a Springing Covenant Period and sized at 4.00 :1.00 during the first quarter ending after a Springing Covenant Event, 3.75 :1.00 during the second quarter ending after a Springing Covenant Event and 3.50 :1.00 during the third and fourth quarters ending after a Springing Covenant Event. Further, if the Company or any of its subsidiaries incurs unsecured indebtedness under the uncapped general indebtedness basket or permitted convertible indebtedness basket of the Credit Agreement in excess of $ 50.0 million in connection with a transaction that is a Springing Covenant Event or during a Springing Covenant Period, then the maximum consolidated senior secured net leverage ratio shall be, or shall automatically step down to, 3.50 :1.00 at the time of such incurrence. The First Amendment also requires that the consolidated interest coverage ratio (as defined in the First Amendment) 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, 2023, the Company was in compliance with all material covenants. 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 First Amendment 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 First Amendment 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 On March 29, 2023, Adtran Networks entered into a $ 16.1 million unsecured revolving line of credit with Norddeutsche Landesbark - Girozentrale (Nord/LB) that bears interest of Euro Short Term Rate plus 1.94 %. The line of credit has a perpetual term that can be terminated by the Company or Nord/LB at any time. As of September 30, 2023 , Adtran Networks borrowed $ 10.6 million under this facility. Prior Nord/LB Revolving Line of Credit On August 8, 2022, Adtran Networks entered into a $ 16.1 million revolving line of credit with Norddeutsche Landesbark - Girozentrale (Nord/LB) that bears interest of Euro Short Term Rate plus 1.4 % and matured in August 2023 . On January 31, 2023, the Company repaid the outstanding borrowings under the Nord/LB revolving line of credit. No amounts are available for future borrowings. Syndicated Credit Agreement Working Capital Line of Credit In September 2018, Adtran Networks entered into a syndicated credit agreement with Bayerische Landesbank and Deutsche Bank AG Branch German Business to borrow up to $ 10.7 million as part of a working capital line of credit. On January 31, 2023, the Company repaid the outstanding borrowings under the syndicated credit agreement working capital line of credit. No amounts are available for future borrowings. DZ Bank Revolving Line of Credit In the fourth quarter of 2022, Adtran Networks entered into a revolving line of credit with DZ Bank to borrow up to $ 9.1 million. Interest on the line of credit reset monthly based on renewal of the loan and was 2.8 % at the time the loan was repaid. On March 12, 2023, the Company repaid the outstanding borrowings under the DZ Bank revolving line of credit. No amounts are available for future borrowings.

Notes Payable

Notes Payable	9 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Notes Payable	13. 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, 2023 September 30, 2023 December 31, 2022 Syndicated credit agreement notes payable $ — $ — $ 24,598 Total Notes Payable $ — $ — $ 24,598 Syndicated Credit Agreement Note Payable In September 2018, Adtran Networks entered into a syndicated credit agreement with Bayerische Landesbank and Deutsche Bank AG Branch German Business to borrow $ 63.7 million. On January 31, 2023, the Company repaid the outstanding borrowings under the syndicated credit agreement note payable. No amounts are available for future borrowings.

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2023
Retirement Benefits [Abstract]
Employee Benefit Plans	14. EMPLOYEE BENEFIT PLANS The Company maintains defined benefit pension plans covering employees in certain foreign countries. In connection with the Business Combination, we acquired $ 29.6 million of additional obligations and $ 22.3 million of assets related to post-employment benefit plans for certain groups of employees at our new operations outside of the U.S. Plans vary depending on the legal, economic, and tax environments of the respective country. For defined benefit plans, accruals for pensions and similar commitments have been included in the results for this year. The new defined benefit plans are for employees in Switzerland, Italy, Israel and India: • In Switzerland, there are two defined benefit pension plans. Both plans provide benefits in the event of retirement, death or disability. The plan's benefits are based on age, years of service, salary and on a participants old age account. The plans are financed by contributions paid by the participants and by the Company. • In Italy, the post-employment benefit plan is required due to statutory provisions. The plan is financed directly by the Company on a pay as you go basis. Employees receive their pension payments as a function of salary, inflation and a notional account. • In Israel, there is a defined benefit pension plan that provides benefits in the event of a participant being dismissed involuntarily, retirement or death. The plan's benefits are based on the higher of the severance benefit required by law or the cash surrender value of the severance benefit component of any qualifying insurance policy or long-term employee benefit fund that is registered in the participants' name. The plan is financed by contributions paid by the Company. • In India, the post-employment benefit plan is required due to statutory provisions. The plan is financed directly by the Company on a pay as you go basis. The Company's net pension liability for all defined benefit pension plans totaled $ 10.7 million and $ 10.6 million as of September 30, 2023 and December 31, 2022, respectively. The following table summarizes the components of net periodic pension cost related to the Company's defined benefit pension plans: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2023 2022 2023 2022 Service cost $ 401 $ 478 $ 1,203 $ 981 Interest cost ( 33 ) 204 ( 99 ) 638 Expected return on plan assets 59 ( 465 ) 177 ( 1,384 ) Amortization of actuarial losses 7 81 20 254 Net periodic pension cost $ 434 $ 298 $ 1,300 $ 489 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 $ 2.8 million and $ 1.2 million during the nine months ended September 30, 2023 and 2022, respectively. Contributions to the defined benefit pension plans for the remainder of 2023 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 $ 0.9 million.

Equity

Equity	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Equity	15. EQUITY Accumulated Other Comprehensive (Loss) Income The following tables present the changes in accumulated other comprehensive (loss) income, net of tax, by component: Three Months Ended September 30, 2023 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance as of June 30, 2023 $ ( 773 ) $ ( 958 ) $ 63,554 $ 385 $ 62,208 Other comprehensive income (loss) before 635 — ( 29,716 ) — ( 29,081 ) Amounts reclassified from accumulated other ( 244 ) ( 83 ) — — ( 327 ) Net current period other comprehensive income (loss) 391 ( 83 ) ( 29,716 ) — ( 29,408 ) Balance as of September 30, 2023 $ ( 382 ) $ ( 1,041 ) $ 33,838 $ 385 $ 32,800 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 ( 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 ) Nine Months Ended September 30, 2023 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance as of December 31, 2022 $ ( 836 ) $ ( 1,016 ) $ 48,180 $ 385 $ 46,713 Other comprehensive income (loss) before 733 — ( 14,098 ) — ( 13,365 ) Amounts reclassified from accumulated other ( 279 ) ( 25 ) — — ( 304 ) Net current period other comprehensive income (loss) 454 ( 25 ) ( 14,098 ) — ( 13,669 ) Less: Comprehensive income attributable to non-controlling interest, net of tax — — 244 — 244 Balance as of September 30, 2023 $ ( 382 ) $ ( 1,041 ) $ 33,838 $ 385 $ 32,800 Nine Months Ended September 30, 2022 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance 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 ) Balance as of September 30, 2022 $ ( 1,872 ) $ ( 5,831 ) $ ( 32,970 ) $ 385 $ ( 40,288 ) The following tables present the details of reclassifications out of accumulated other comprehensive loss: Three Months Ended September 30, 2023 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized loss on sales of securities $ 321 Net investment (loss) gain Defined benefit plan adjustments – actuarial loss 120 (1) Total reclassifications for the period, before tax 441 Tax benefit ( 114 ) Total reclassifications for the period, net of tax $ 327 (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, 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. Nine Months Ended September 30, 2023 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized loss on sales of securities $ 367 Net investment (loss) gain Defined benefit plan adjustments – actuarial loss 36 (1) Total reclassifications for the period, before tax 403 Tax benefit ( 99 ) Total reclassifications for the period, net of tax $ 304 (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. The following table presents the tax effects related to the change in each component of other comprehensive (loss) income: Three Months Ended Three Months Ended September 30, 2023 September 30, 2022 (In thousands) Before-Tax Tax Net-of-Tax Before-Tax Tax Net-of-Tax Unrealized gain (loss) on available-for-sale $ 836 $ ( 201 ) $ 635 $ ( 334 ) $ 80 $ ( 254 ) Reclassification adjustment for amounts related to ( 321 ) 77 ( 244 ) ( 187 ) 45 ( 142 ) Reclassification adjustment for amounts related to ( 120 ) 37 ( 83 ) ( 171 ) 53 ( 118 ) Foreign currency translation adjustments ( 29,716 ) — ( 29,716 ) ( 23,172 ) — ( 23,172 ) Total Other Comprehensive Loss $ ( 29,321 ) $ ( 87 ) $ ( 29,408 ) $ ( 23,864 ) $ 178 $ ( 23,686 ) Nine Months Ended Nine Months Ended September 30, 2023 September 30, 2022 (In thousands) Before-Tax Tax Net-of-Tax Before-Tax Tax Net-of-Tax Unrealized gain (loss) on available-for-sale $ 964 $ ( 231 ) $ 733 $ ( 2,392 ) $ 574 $ ( 1,818 ) Reclassification adjustment for amounts related to ( 367 ) 88 ( 279 ) 655 ( 157 ) 498 Reclassification adjustment for amounts related to ( 36 ) 11 ( 25 ) ( 316 ) 98 ( 218 ) Foreign currency translation adjustments ( 14,098 ) — ( 14,098 ) ( 26,930 ) — ( 26,930 ) Total Other Comprehensive Loss $ ( 13,537 ) $ ( 132 ) $ ( 13,669 ) $ ( 28,983 ) $ 515 $ ( 28,468 )

Redeemable Non-controlling Inte

Redeemable Non-controlling Interest	9 Months Ended
	Sep. 30, 2023
Redeemable Noncontrolling Interest, Equity, Carrying Amount [Abstract]
Redeemable Non-controlling Interest	16. REDEEMABLE NON-CONTROLLING INTEREST The following table summarizes the redeemable non-controlling interest activity for the nine months ended September 30, 2023: Nine Months Ended (In thousands) September 30, 2023 Balance at beginning of period $ — Reclassification of non-controlling interests 443,757 Redemption of redeemable non-controlling interest ( 1,558 ) Net income attributable to redeemable non-controlling interests 8,605 Annual recurring compensation earned ( 8,605 ) Translation adjustment ( 10,291 ) Adtran Networks stock option exercises 13 Balance as of September 30, 2023 $ 431,921 Annual recurring compensation payable on untendered outstanding shares under the DPLTA must be recognized as it is accrued. For the three and nine months ended September 30, 2023 , we have recognized $ 2.9 million and $ 8.6 million, respectively, representing the portion of the annual recurring cash compensation to the non-controlling shareholders accrued during such periods, which will be paid after the ordinary general shareholders' meeting of Adtran Networks beginning in 2024. See Note 1 and Note 20 for additional information on RNCI and the annual dividend .

Loss per share

Loss per share	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
(Loss) Earnings 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) 2023 2022 2023 2022 Numerator Net loss attributable to ADTRAN Holdings, Inc. $ ( 72,735 ) $ ( 41,934 ) $ ( 140,533 ) $ ( 40,918 ) Denominator Weighted average number of shares – basic 78,389 73,036 78,378 57,175 Effect of dilutive securities Stock options — — — — PSUs, RSUs and restricted stock — — — — Weighted average number of shares – diluted 78,389 73,036 78,378 57,175 Loss per share attributable to ADTRAN Holdings, Inc. – basic $ ( 0.93 ) $ ( 0.57 ) $ ( 1.79 ) $ ( 0.72 ) Loss per share attributable to ADTRAN Holdings, Inc. – diluted $ ( 0.93 ) $ ( 0.57 ) $ ( 1.79 ) $ ( 0.72 ) For the three months ended September 30, 2023 and 2022 , 0.5 million and 4 thousand shares, respectively, and for the nine months ended September 30, 2023 and 2022 , 0.4 million and 4 thousand shares, respectively, 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, 2023 and 2022 , 2.6 million and 0.1 million stock options, respectively, and for the nine months ended September 30, 2023 and 2022 , 1.4 million and 0.2 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, 2023
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 which support the Company's Subscriber, Access & Aggregation, and Optical Networking Solutions. 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 Services & Support segment offers a comprehensive portfolio of network design, implementation, maintenance and cloud-hosted services supporting its Subscriber, Access & 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 the Company's Mosaic One platform that manages end-to-end network and service optimization for both fiber access infrastructure and mesh Wi-Fi connectivity. The Company backs these services with a global support organization that offers on-site and off-site support services with varying SLAs. 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 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 the Company's reportable segments: Three Months Ended September 30, 2023 September 30, 2022 (In thousands) Revenue Gross Profit Revenue Gross Profit Network Solutions $ 228,564 $ 47,277 $ 304,940 $ 82,334 Services & Support 43,767 26,960 35,769 20,693 Total $ 272,331 $ 74,237 $ 340,709 $ 103,027 Nine Months Ended September 30, 2023 September 30, 2022 (In thousands) Revenue Gross Profit Revenue Gross Profit Network Solutions $ 793,984 $ 176,607 $ 599,306 $ 186,126 Services & Support 129,637 77,991 67,959 33,723 Total $ 923,621 $ 254,598 $ 667,265 $ 219,849 For the three months ended September 30, 2023 and 2022 , $ 1.5 million and $ 1.1 million, respectively, of depreciation expense was included in gross profit for our Network Solutions segment. For the nine months ended September 30, 2023 and 2022 , $ 4.5 million and $ 1.6 million, respectively, of depreciation expense was included in gross profit for our Network Solutions segment. For the three months ended September 30, 2023 and 2022 , $ 2.4 thousand of depreciation expense was included in gross profit for our Services & Support segment. For the nine months ended September 30, 2023 and 2022 , $ 7.3 thousand and $ 8.0 thousand, respectively, of depreciation expense was included in gross profit for our Services & Support segment. 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 Adtran Networks 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 Adtran Networks, the Company has recast these revenues such that ADTRAN’s former Access & Aggregation revenue is combined with a portion of the applicable Adtran Networks solutions to create Access & Aggregation Solutions, ADTRAN’s former Subscriber Solutions & Experience revenue is combined with a portion of the applicable Adtran Networks 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 Adtran Networks' 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) 2023 2022 2023 2022 Optical Networking Solutions $ 116,200 $ 118,845 $ 406,952 $ 118,845 Access & Aggregation Solutions 94,646 88,189 294,183 278,273 Subscriber Solutions 61,485 133,675 222,486 270,147 Total $ 272,331 $ 340,709 $ 923,621 $ 667,265 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) 2023 2022 2023 2022 United States $ 111,494 $ 169,669 $ 375,254 $ 374,470 Germany 60,347 64,234 212,171 71,945 United Kingdom 41,242 46,569 150,710 123,477 Other international 59,248 60,237 185,486 97,373 Total $ 272,331 $ 340,709 $ 923,621 $ 667,265

Liability for Warranty Returns

Liability for Warranty Returns	9 Months Ended
	Sep. 30, 2023
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 $ 6.6 million and $ 7.2 million as of September 30, 2023 and December 31, 2022 , respectively, and is included in accrued expenses and other liabilities in the Condensed Consolidated Balance Sheets. The warranty expense and write-off activity for the three and nine months ended September 30, 2023 and 2022 are summarized as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2023 2022 2023 2022 Balance at beginning of period $ 6,831 $ 4,842 $ 7,196 $ 5,403 Plus: Adtran Networks acquisition — 3,756 — 3,756 Plus: Amounts charged to cost and expenses 752 616 2,289 1,727 Plus: Foreign currency translation adjustments ( 73 ) — ( 33 ) — Less: Deductions ( 943 ) ( 613 ) ( 2,885 ) ( 2,285 ) Balance at end of period $ 6,567 $ 8,601 $ 6,567 $ 8,601

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	20. COMMITMENTS AND CONTINGENCIES Legal Matters From time to time, the Company is 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, the Company is unable to predict the outcome of or estimate the possible loss or range of loss, if any, associated with such legal matters. Adtran Networks Legal Matter On May 8, 2023, Adtran Networks SE and its subsidiary, ADVA Optical Networking North America, Inc. (together, “Adtran Networks”), filed a lawsuit in the U.S District Court for the Eastern District of Texas (“EDTX”) against Huawei Technologies Co. Ltd (“Huawei”) seeking a declaration from the court that Huawei violated its commitments to negotiate in good faith and to license standard essential patents (“SEPs”), to the extent any SEPs are practiced by Adtran Networks, on Fair, Reasonable and Non-Discriminatory (“FRAND”) terms and conditions. The case also sought to obtain a ruling by the EDTX that Adtran Networks has complied with its own commitments and requested that the Court establish FRAND terms and conditions for obtaining a FRAND license on any SEPs to the extent they are practiced by Adtran Networks. The lawsuit further sought to enjoin Huawei from enforcing certain Huawei patents that Adtran Networks considers invalid and/or not practiced, and Adtran Networks alleged that Huawei had infringed upon an Adtran Networks patent. On July 20, 2023, Adtran Networks SE was served with a complaint filed by Huawei against Adtran Networks SE in the District Court München I, Germany, alleging that certain of its products infringe upon one of Huawei’s patents. On August 22, 2023, Adtran Networks entered into a settlement agreement with Huawei pursuant to which the parties agreed to, among other things, dismiss the lawsuits described above. DPLTA Exit and Recurring Compensation Costs Pursuant to the terms of the DPLTA, each Adtran Networks shareholder (other than the Company) has received an offer to elect either (1) to remain an Adtran Networks shareholder and receive from us an Annual Recurring Compensation payment, or (2) to receive Exit Compensation plus guaranteed interest. The guaranteed interest under the Exit Compensation is calculated from the effective date of the DPLTA to the date the shares are tendered, less any Annual Recurring Compensation paid. The guaranteed interest rate is 5.0 % plus a variable component (according to the German Civil Code) that was 3.12 % as of September 30, 2023. Assuming all the minority holders of currently outstanding Adtran Networks shares were to elect the second option, we would be obligated to make aggregate Exit Compensation payments, including guaranteed interest, of approximately € 325.3 million or approximately $ 344.2 million, based on an exchange rate as of September 30, 2023 and reflecting interest accrued through September 30, 2023 during the pendency of the appraisal proceedings discussed below. Shareholders electing the first option of Annual Recurring Compensation may later elect the second option. The opportunity for outside Adtran Networks shareholders to tender Adtran Networks shares in exchange for Exit Compensation had been scheduled to expire on March 16, 2023 . However, due to the appraisal proceedings that have been initiated in accordance with applicable German law, this time period for tendering shares has been extended pursuant to the German Stock Corporation Act ( Aktiengesetz ) and will end two months after the date on which a final decision in such appraisal proceedings has been published in the Federal Gazette ( Bundesanzeiger ). Our obligation to pay Annual Recurring Compensation under the DPLTA is a continuing payment obligation, which will amount to approximately € 10.6 million or $ 11.2 million (based on the current exchange rate) per year assuming none of the minority Adtran Networks shareholders were to elect Exit Compensation. The foregoing amounts do not reflect any potential increase in payment obligations that we may have depending on the outcome of ongoing appraisal proceedings in Germany. During the three and nine months ended September 30, 2023, we accrued $ 2.9 million and $ 8.6 million in Annual Recurring Compensation, which was reflected as a reduction to retained (deficit) earnings, respectively. For the three and nine months ended September 30, 2023 , less than 1 thousand shares and 64 thousand shares, respectively, of Adtran Networks stock was tendered to the Company and Exit Compensation payments of approximately € 8 thousand and € 1.1 million, respectively, or appro ximately $ 9 thousand and $ 1.2 million, respectively, based on an exchange rate as of September 30, 2023, were paid to Adtran Networks shareholders. Performance Bonds Certain 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, 2023 and December 31, 2022, we had commitments related to these bonds totaling $ 11.8 million and $ 22.0 million, respectively, which expire at various dates through April 2031 . 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 The Company purchases 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, 2023, purchase commitments totaled $ 308.4 million.

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Restructuring	21. RESTRUCTURING During the fourth quarter of 2022, the Company initiated a restructuring program designed to optimize the assets and business processes, and information technology systems of the Company in relation to the Business Combination with Adtran Networks. The restructuring program is expected to maximize cost synergies by realizing operation scale, combining sales channels, streamlining corporate and general and administrative functions, including human capital resources and combining sourcing and production costs. This restructuring program is expected to be completed in late 2024. In February 2019, the Company announced the restructuring of a certain portion of its workforce predominantly in Germany, which included the closure of a subsidiary's office location in Munich, Germany accompanied by relocation or severance benefits for the affected employees. Voluntary early retirement was offered to certain other employees and was announced in March 2019 and again in August 2020. This plan was completed in 2021 and all amounts were paid in 2022. During the three and nine months ended September 30, 2023, we recognized a certain write down of inventory of $ 21.0 million due to a restructuring discontinuation of certain product lines within our Network Solutions segment. There was no write down of inventory during the three and nine months ended September 30, 2022. See Note 7, Inventory, for additional information regarding the write down of inventory. A reconciliation of the beginning and ending restructuring liabilities, which is included in accrued wages and benefits in the Condensed Consolidated Balance Sheets as of September 30, 2023 and December 31, 2022, is as follows: Three Months Ended Nine Months Ended (In thousands) September 30, 2023 September 30, 2023 Balance at beginning of period $ 6,452 $ 159 Plus: Amounts charged to cost and expense 3,830 12,135 Less: Amounts paid ( 4,729 ) ( 6,741 ) Balance as of September 30, 2023 $ 5,553 $ 5,553 For the Year Ended (In thousands) December 31, 2022 Balance as of December 31, 2021 $ 1,514 Plus: Amounts charged to cost and expense 1,629 Less: Amounts paid ( 2,984 ) Balance as of December 31, 2022 $ 159 Restructuring expenses included in the Condensed Consolidated Statements of Loss are for the three and nine months ended September 30, 2023 and 2022: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2023 2022 2023 2022 Network Solutions - Cost of revenue $ 611 $ — $ 669 $ — Network Solutions - Inventory write down 21,043 — 21,043 — Services & Support - Cost of revenue ( 24 ) — ( 6 ) — Cost of revenue $ 21,630 $ — $ 21,706 $ — Selling, general and administrative expenses 3,387 — 6,960 2 Research and development expenses ( 144 ) — 4,512 — Total restructuring expenses $ 24,873 $ — $ 33,178 $ 2 The following table represents the components of restructuring expenses by geographic area for the three and nine months ended September 30, 2023 and 2022: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2023 2022 2023 2022 United States $ 22,598 $ — $ 25,217 $ 2 International 2,275 — 7,961 — Total restructuring expenses $ 24,873 $ — $ 33,178 $ 2

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	22. SUBSEQUENT EVENTS Dividend Suspension On November 6, 2023, the Board of Directors suspended the Company’s quarterly cash dividend which will be redirected to reduce debt and interest expense and support the Company's capital efficiency program. The payment of any future dividends will be at the discretion of the Board of Directors and will depend on the Company’s financial condition, results of operations, capital requirements, and any other factors deemed relevant by the Board of Directors. Business Efficiency Program On November 6, 2023, due to the uncertainty around the current macroeconomic environment and its impact on customer spending levels, the Company’s management determined to implement a comprehensive business efficiency program, which includes (i) a cost efficiency program targeting the reduction of ongoing operating expenses, and (ii) a capital efficiency program, which includes a site consolidation plan exploring the partial sale of owned real estate and the suspension of the quarterly dividend. See Part II, Item 5 (a) of this report for additional information regarding the business efficiency program.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
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. The December 31, 2022 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 Amendment No. 1 to the ADTRAN Holdings, Inc. Annual Report on Form 10-K for the year ended December 31, 2022 , filed with the SEC on August 14, 2023.
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, estimates of intangible assets upon measurement, estimated pension liability and fair value of investments and estimated contingent liabilities. 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 supply chain constraints, inflationary pressures, the energy crisis, currency fluctuations and political tensions as of September 30, 2023, 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 as sets, revenue recognition and costs of revenue. Future conditions related to supply chain constraints, inflationary pressures, the energy crisis, rising interest rates, instability in the financial services industry, currency fluctuations and political tensions could result in further impacts to the Company's consolidated financial statements in future reporting periods
Redeemable Non-Controlling Interest	Redeemable Non-Controlling Interest As of September 30, 2023 and December 31, 2022, the non-controlling Adtran Networks stockholders’ equity ownership percentage in Adtran Networks was approximately 34.6 % and 34.7 %, respectively. As a result of the effectiveness of the DPLTA on January 16, 2023, the Adtran Networks shares, representing the equity interest in Adtran Networks held by holders other than the Company, can be tendered at any time and are, therefore, redeemable and must be classified outside stockholders’ equity. Therefore, the permanent equity noncontrolling interest balance was reclassified to redeemable non-controlling interest on January 16, 2023 and was remeasured to fair value based on the trading market price of the Adtran Networks shares. Subsequently, the carrying value of the RNCI is adjusted to its maximum redemption value at each reporting date when the maximum redemption value is greater than the initial carrying amount of the RNCI. However, the RNCI will be remeasured using the current exchange rate at each reporting date as long as the RNCI is currently redeemable. For the period of time that the DPLTA is in effect, the RNCI will continue to be presented as RNCI outside of stockholders’ equity in the Condensed Consolidated Balance Sheets. See Note 16 for additional information on RNCI .
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.
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted There are currently no accounting pronouncements not yet adopted that are expected to have a material effect on the Condensed Consolidated Financial Statements.

Business Combination (Tables)

Business Combination (Tables)	9 Months Ended
	Sep. 30, 2023
Business Combinations [Abstract]
Summary of Purchase Price for Business Combination	The following table summarizes the purchase price for the Adtran Networks business combination: (In thousands, except shares, share price and exchange ratio) Purchase Price Adtran Networks 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 Adtran Networks 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 Final Purchase Price Allocation of Assets Acquired and Liabilities Assumed	The following table summarizes the final purchase price allocation for each major class of assets acquired and liabilities assumed in the Business Combination (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 200,331 Prepaid expenses and other current assets 28,208 Property plant and equipment 55,480 Deferred tax assets 1,759 Intangibles 403,780 Other non-current assets 31,074 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, net ( 4,898 ) Tax liabilities ( 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 ( 61,040 ) Total net assets acquired $ 544,217 Goodwill $ 350,458
Summary of Fair Value of Intangible Assets Acquired	The fair value of the identifiable 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 $ 291,925 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 $ 403,780 (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 information also does not include any integration costs that the Company has incurred and may continue to incur related to the Business Combination as part of combining the operations of the companies. Three Months Ended Nine Months Ended (In thousands) September 30, 2022 September 30, 2022 Revenue $ 368,192 $ 1,053,510 Net loss $ ( 48,084 ) $ ( 60,494 )

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2023
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, 2023 September 30, 2022 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Optical Networking Solutions $ 94,592 $ 21,608 $ 116,200 $ 103,011 $ 15,834 $ 118,845 Access & Aggregation Solutions 81,051 13,595 94,646 76,591 11,598 88,189 Subscriber Solutions 52,921 8,564 61,485 125,338 8,337 133,675 Total $ 228,564 $ 43,767 $ 272,331 $ 304,940 $ 35,769 $ 340,709 Nine Months Ended September 30, 2023 September 30, 2022 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Optical Networking Solutions $ 342,390 $ 64,562 $ 406,952 $ 103,011 $ 15,834 $ 118,845 Access & Aggregation Solutions 254,868 39,315 294,183 243,396 34,877 278,273 Subscriber Solutions 196,726 25,760 222,486 252,899 17,248 270,147 Total $ 793,984 $ 129,637 $ 923,621 $ 599,306 $ 67,959 $ 667,265 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) 2023 2022 2023 2022 Optical Networking Solutions $ 116,200 $ 118,845 $ 406,952 $ 118,845 Access & Aggregation Solutions 94,646 88,189 294,183 278,273 Subscriber Solutions 61,485 133,675 222,486 270,147 Total $ 272,331 $ 340,709 $ 923,621 $ 667,265
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, 2023 December 31, 2022 Accounts receivable, net $ 229,333 $ 279,435 Contract assets (1) $ 888 $ 1,852 Unearned revenue $ 49,832 $ 41,193 Non-current unearned revenue $ 23,501 $ 19,239

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2023
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, 2023 (In thousands) Deferred Tax Assets (Liabilities) Valuation Allowance Deferred Tax Assets (Liabilities), net Domestic $ 84,274 $ ( 3,177 ) $ 81,097 International ( 26,975 ) ( 1,839 ) ( 28,814 ) Total $ 57,299 $ ( 5,016 ) $ 52,283 As of December 31, 2022 (In thousands) Deferred Tax Assets (Liabilities) Valuation Allowance Deferred Tax Assets (Liabilities), net Domestic $ 61,726 $ ( 3,177 ) $ 58,549 International ( 50,315 ) ( 2,024 ) ( 52,339 ) Total $ 11,411 $ ( 5,201 ) $ 6,210

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2023
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, 2022 and September 30, 2023 and the changes that occurred during the nine months ended September 30, 2023: Number of Weighted Avg. Grant Date Fair Value Unvested RSUs and restricted stock outstanding, December 31, 2022 1,086 $ 17.54 RSUs and restricted stock granted 1,484 $ 16.58 RSUs and restricted stock vested ( 56 ) $ 20.37 RSUs and restricted stock forfeited ( 51 ) $ 16.42 Unvested RSUs and restricted stock outstanding, September 30, 2023 2,463 $ 17.01
Summary of Stock Options Outstanding	The following table summarizes the ADTRAN Holdings, Inc. stock options outstanding as of December 31, 2022 and September 30, 2023 and the changes that occurred during the nine months ended September 30, 2023: Number of Weighted Avg. Weighted Avg. Aggregate Stock options outstanding, December 31, 2022 3,148 $ 14.37 3.42 $ 16,251 Stock options granted 7 $ 12.17 Stock options exercised ( 8 ) $ 8.72 Stock options forfeited ( 40 ) $ 11.93 Stock options expired ( 33 ) $ 16.44 Stock options outstanding, September 30, 2023 3,074 $ 14.39 2.68 $ 736 Stock options exercisable, September 30, 2023 1,691 $ 15.88 1.23 $ 556
Adtran Networks SE [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Summary of Stock Options Outstanding	The following table summarizes the Adtran Networks stock options outstanding as of December 31, 2022 and September 30, 2023 and the changes that occurred during the nine months ended September 30, 2023: Number of (In thousands) Weighted (Per share) Weighted Avg. Aggregate Value (In thousands) Stock options outstanding, December 31, 2022 81 $ 8.58 4.00 $ 1,222 Stock options exercised ( 13 ) $ 8.22 Stock options forfeited ( 9 ) $ 10.58 Stock options expired ( 1 ) $ 9.20 Stock options outstanding, September 30, 2023 58 $ 8.18 3.39 $ 746 Stock options exercisable, September 30, 2023 12 $ 6.03 1.48 $ 182

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2023
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 December 31, 2022: As of December 31, 2022 Amortized Gross Unrealized Fair (In thousands) Cost Gains Losses Value Corporate bonds $ 2,538 $ 5 $ ( 81 ) $ 2,462 Municipal fixed-rate bonds 185 — ( 5 ) 180 Asset-backed bonds 818 1 ( 24 ) 795 Mortgage/Agency-backed bonds 1,853 — ( 105 ) 1,748 U.S. government bonds 3,870 3 ( 188 ) 3,685 Foreign government bonds 407 — ( 24 ) 383 Available-for-sale debt securities held at fair value $ 9,671 $ 9 $ ( 427 ) $ 9,253
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) 2023 2022 2023 2022 Gross realized gain on debt securities $ 5 $ 1 $ 9 $ 14 Gross realized loss on debt securities ( 317 ) ( 116 ) ( 355 ) ( 242 ) Total loss recognized, net $ ( 312 ) $ ( 115 ) $ ( 346 ) $ ( 228 )
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) 2023 2022 2023 2022 Unrealized gain (loss) on equity securities held $ ( 1,130 ) $ ( 1,217 ) $ 1,404 $ ( 8,849 ) Realized gain (loss) on equity securities sold ( 1 ) ( 1,358 ) 13 ( 1,675 ) Total gain (loss) recognized, net $ ( 1,131 ) $ ( 2,575 ) $ 1,417 $ ( 10,524 )
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, 2023 Using (In thousands) Fair Value Quoted Prices Significant Significant Unobservable Inputs Cash equivalents U.S. government securities $ — $ — $ — $ — Money market funds 5,245 5,245 — — Commercial paper — — — — Total cash equivalents $ 5,245 $ 5,245 $ - $ — Marketable equity securities Marketable equity securities – various industries 815 815 — — Deferred compensation plan assets 24,364 24,364 — — Total long-term investments $ 25,179 $ 25,179 $ — $ — Total $ 30,424 $ 30,424 $ — $ — Fair Value Measurements as of December 31, 2022 Using (In thousands) Fair Value Quoted Prices Significant Significant Unobservable Inputs Cash equivalents Money market funds $ 228 $ 228 $ — $ — Total cash equivalents $ 228 $ 228 $ — $ — Available-for-sale debt securities Corporate bonds $ 2,462 $ — $ 2,462 $ — Municipal fixed-rate bonds 180 — 180 — Asset-backed bonds 795 — 795 — Mortgage/Agency-backed bonds 1,748 — 1,748 — U.S. government bonds 3,685 3,685 — — Foreign government bonds 383 — 383 — Marketable equity securities Marketable equity securities – various industries 810 810 — — Deferred compensation plan assets 22,942 22,942 — — Total short-term and long-term investments $ 33,005 $ 27,437 $ 5,568 $ - Total $ 33,233 $ 27,665 $ 5,568 $ —

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2023
Inventory Disclosure [Abstract]
Components of Inventory	Inventory consisted of the following: As of As of (In thousands) September 30, 2023 December 31, 2022 Raw materials $ 156,287 $ 186,346 Work in process 15,648 12,087 Finished goods 202,036 229,098 Total inventory, net $ 373,971 $ 427,531

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2023
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, 2023 December 31, 2022 Engineering and other equipment $ 179,049 $ 170,785 Building 85,966 82,932 Computer hardware and software 97,192 80,455 Building and land improvements 51,284 47,861 Furniture and fixtures 23,686 22,403 Land 5,325 5,364 Total property, plant and equipment 442,502 409,800 Less: accumulated depreciation ( 323,879 ) ( 299,101 ) Total property, plant and equipment, net $ 118,623 $ 110,699

Goodwill (Tables)

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2023
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, 2023 are as follows: (In thousands) Network Solutions Services & Support Total As of December 31, 2022 $ 298,280 $ 83,444 $ 381,724 Goodwill impairment — ( 37,500 ) ( 37,500 ) Foreign currency translation adjustments ( 3,873 ) ( 1,268 ) ( 5,141 ) As of September 30, 2023 $ 294,407 $ 44,676 $ 339,083

Intangible Assets (Tables)

Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2023
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Summary of Intangible Assets	Intangible assets consisted of the following: As of September 30, 2023 As of December 31, 2022 (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 $ 53,247 $ ( 14,490 ) $ 38,757 $ 55,517 $ ( 12,772 ) $ 42,745 Backlog 1.6 55,017 ( 49,061 ) 5,956 55,782 ( 22,725 ) 33,057 Developed technology 8.5 316,083 ( 49,944 ) 266,139 320,364 ( 21,856 ) 298,508 Licensed technology 9.0 5,900 ( 3,633 ) 2,267 5,900 ( 3,141 ) 2,759 Licensing agreements 8.5 560 ( 353 ) 207 560 ( 298 ) 262 Patents 7.3 500 ( 483 ) 17 500 ( 431 ) 69 Trade names 3.0 28,461 ( 13,109 ) 15,352 29,066 ( 5,255 ) 23,811 Total $ 459,768 $ ( 131,073 ) $ 328,695 $ 467,689 $ ( 66,478 ) $ 401,211
Estimated Future Amortization Expense Related to Intangible Assets	Estimated future amortization expense of intangible assets is as follows: As of (In thousands) September 30, 2023 2023 $ 13,770 2024 56,800 2025 45,504 2026 42,290 2027 40,941 Thereafter 129,390 Total $ 328,695

Hedging (Tables)

Hedging (Tables)	9 Months Ended
	Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Fair Values of Derivative Instruments	The fair values of the Company's derivative instruments recorded in the Condensed Consolidated Balance Sheet as of September 30, 2023 and December 31, 2022 were as follows: (In thousands) Balance Sheet Location September 30, 2023 December 31, 2022 Derivatives Not Designated as Hedging Instruments (Level 2): Foreign exchange contracts – derivative assets Other receivables $ 7,530 $ 11,992 Foreign exchange contracts – derivative liabilities Accounts payable $ ( 10 ) $ ( 633 ) Total derivatives $ 7,520 $ 11,359 The change in the fair values of the Company's derivative instruments recorded in the Condensed Consolidated Statements of Loss during the three and nine months ended September 30, 2023 and 2022 were as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) Income Statement 2023 2022 2023 2022 Derivatives Not Designated as Hedging Instruments: Foreign exchange contracts Other income, net $ 1,012 $ — $ 1,076 $ —

Revolving Credit Agreements (Ta

Revolving Credit Agreements (Tables)	9 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Carrying Amount of Current and Non-Current Revolving Agreements	The carrying amounts of the Company's current and non-current revolving credit agreements in its Condensed Consolidated Balance Sheets were as follows: As of As of (In thousands) September 30, 2023 December 31, 2022 New Nord/LB revolving line of credit $ 10,580 $ — Nord/LB revolving line of credit — 16,091 Syndicated credit agreement working capital line of credit — 10,727 DZ bank revolving line of credit — 9,118 Total current revolving credit agreements $ 10,580 $ 35,936 As of As of (In thousands) September 30, 2023 December 31, 2022 Wells Fargo credit agreement $ 200,000 $ 60,000 Total non-current revolving credit agreement $ 200,000 $ 60,000

Notes Payable (Tables)

Notes Payable (Tables)	9 Months Ended
	Sep. 30, 2023
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, 2023 September 30, 2023 December 31, 2022 Syndicated credit agreement notes payable $ — $ — $ 24,598 Total Notes Payable $ — $ — $ 24,598

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2023
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 the Company's defined benefit pension plans: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2023 2022 2023 2022 Service cost $ 401 $ 478 $ 1,203 $ 981 Interest cost ( 33 ) 204 ( 99 ) 638 Expected return on plan assets 59 ( 465 ) 177 ( 1,384 ) Amortization of actuarial losses 7 81 20 254 Net periodic pension cost $ 434 $ 298 $ 1,300 $ 489

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax, by Component	The following tables present the changes in accumulated other comprehensive (loss) income, net of tax, by component: Three Months Ended September 30, 2023 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance as of June 30, 2023 $ ( 773 ) $ ( 958 ) $ 63,554 $ 385 $ 62,208 Other comprehensive income (loss) before 635 — ( 29,716 ) — ( 29,081 ) Amounts reclassified from accumulated other ( 244 ) ( 83 ) — — ( 327 ) Net current period other comprehensive income (loss) 391 ( 83 ) ( 29,716 ) — ( 29,408 ) Balance as of September 30, 2023 $ ( 382 ) $ ( 1,041 ) $ 33,838 $ 385 $ 32,800 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 ( 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 ) Nine Months Ended September 30, 2023 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance as of December 31, 2022 $ ( 836 ) $ ( 1,016 ) $ 48,180 $ 385 $ 46,713 Other comprehensive income (loss) before 733 — ( 14,098 ) — ( 13,365 ) Amounts reclassified from accumulated other ( 279 ) ( 25 ) — — ( 304 ) Net current period other comprehensive income (loss) 454 ( 25 ) ( 14,098 ) — ( 13,669 ) Less: Comprehensive income attributable to non-controlling interest, net of tax — — 244 — 244 Balance as of September 30, 2023 $ ( 382 ) $ ( 1,041 ) $ 33,838 $ 385 $ 32,800 Nine Months Ended September 30, 2022 (In thousands) Unrealized Defined Foreign ASU 2018-02 Adoption Total Balance 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 ) Balance as of September 30, 2022 $ ( 1,872 ) $ ( 5,831 ) $ ( 32,970 ) $ 385 $ ( 40,288 )
Reclassifications Out of Accumulated Other Comprehensive Loss	The following tables present the details of reclassifications out of accumulated other comprehensive loss: Three Months Ended September 30, 2023 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized loss on sales of securities $ 321 Net investment (loss) gain Defined benefit plan adjustments – actuarial loss 120 (1) Total reclassifications for the period, before tax 441 Tax benefit ( 114 ) Total reclassifications for the period, net of tax $ 327 (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, 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. Nine Months Ended September 30, 2023 (In thousands) Amount Affected Line Item in the Unrealized gain (loss) on available-for-sale securities: Net realized loss on sales of securities $ 367 Net investment (loss) gain Defined benefit plan adjustments – actuarial loss 36 (1) Total reclassifications for the period, before tax 403 Tax benefit ( 99 ) Total reclassifications for the period, net of tax $ 304 (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.
Tax Effects Related to the Change in Each Component of Other Comprehensive Income (Loss)	The following table presents the tax effects related to the change in each component of other comprehensive (loss) income: Three Months Ended Three Months Ended September 30, 2023 September 30, 2022 (In thousands) Before-Tax Tax Net-of-Tax Before-Tax Tax Net-of-Tax Unrealized gain (loss) on available-for-sale $ 836 $ ( 201 ) $ 635 $ ( 334 ) $ 80 $ ( 254 ) Reclassification adjustment for amounts related to ( 321 ) 77 ( 244 ) ( 187 ) 45 ( 142 ) Reclassification adjustment for amounts related to ( 120 ) 37 ( 83 ) ( 171 ) 53 ( 118 ) Foreign currency translation adjustments ( 29,716 ) — ( 29,716 ) ( 23,172 ) — ( 23,172 ) Total Other Comprehensive Loss $ ( 29,321 ) $ ( 87 ) $ ( 29,408 ) $ ( 23,864 ) $ 178 $ ( 23,686 ) Nine Months Ended Nine Months Ended September 30, 2023 September 30, 2022 (In thousands) Before-Tax Tax Net-of-Tax Before-Tax Tax Net-of-Tax Unrealized gain (loss) on available-for-sale $ 964 $ ( 231 ) $ 733 $ ( 2,392 ) $ 574 $ ( 1,818 ) Reclassification adjustment for amounts related to ( 367 ) 88 ( 279 ) 655 ( 157 ) 498 Reclassification adjustment for amounts related to ( 36 ) 11 ( 25 ) ( 316 ) 98 ( 218 ) Foreign currency translation adjustments ( 14,098 ) — ( 14,098 ) ( 26,930 ) — ( 26,930 ) Total Other Comprehensive Loss $ ( 13,537 ) $ ( 132 ) $ ( 13,669 ) $ ( 28,983 ) $ 515 $ ( 28,468 )

Redeemable Non-controlling In_2

Redeemable Non-controlling Interest (Tables)	9 Months Ended
	Sep. 30, 2023
Redeemable Noncontrolling Interest, Equity, Carrying Amount [Abstract]
Summary of Redeemable Non-controlling Interest Activity	The following table summarizes the redeemable non-controlling interest activity for the nine months ended September 30, 2023: Nine Months Ended (In thousands) September 30, 2023 Balance at beginning of period $ — Reclassification of non-controlling interests 443,757 Redemption of redeemable non-controlling interest ( 1,558 ) Net income attributable to redeemable non-controlling interests 8,605 Annual recurring compensation earned ( 8,605 ) Translation adjustment ( 10,291 ) Adtran Networks stock option exercises 13 Balance as of September 30, 2023 $ 431,921

Loss per share (Tables)

Loss per share (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Summary of Calculation of Basic and Diluted Loss Earnings 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) 2023 2022 2023 2022 Numerator Net loss attributable to ADTRAN Holdings, Inc. $ ( 72,735 ) $ ( 41,934 ) $ ( 140,533 ) $ ( 40,918 ) Denominator Weighted average number of shares – basic 78,389 73,036 78,378 57,175 Effect of dilutive securities Stock options — — — — PSUs, RSUs and restricted stock — — — — Weighted average number of shares – diluted 78,389 73,036 78,378 57,175 Loss per share attributable to ADTRAN Holdings, Inc. – basic $ ( 0.93 ) $ ( 0.57 ) $ ( 1.79 ) $ ( 0.72 ) Loss per share attributable to ADTRAN Holdings, Inc. – diluted $ ( 0.93 ) $ ( 0.57 ) $ ( 1.79 ) $ ( 0.72 )

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Revenue and Gross Profit of Reportable Segments	The following tables present information about the revenue and gross profit of the Company's reportable segments: Three Months Ended September 30, 2023 September 30, 2022 (In thousands) Revenue Gross Profit Revenue Gross Profit Network Solutions $ 228,564 $ 47,277 $ 304,940 $ 82,334 Services & Support 43,767 26,960 35,769 20,693 Total $ 272,331 $ 74,237 $ 340,709 $ 103,027 Nine Months Ended September 30, 2023 September 30, 2022 (In thousands) Revenue Gross Profit Revenue Gross Profit Network Solutions $ 793,984 $ 176,607 $ 599,306 $ 186,126 Services & Support 129,637 77,991 67,959 33,723 Total $ 923,621 $ 254,598 $ 667,265 $ 219,849
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, 2023 September 30, 2022 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Optical Networking Solutions $ 94,592 $ 21,608 $ 116,200 $ 103,011 $ 15,834 $ 118,845 Access & Aggregation Solutions 81,051 13,595 94,646 76,591 11,598 88,189 Subscriber Solutions 52,921 8,564 61,485 125,338 8,337 133,675 Total $ 228,564 $ 43,767 $ 272,331 $ 304,940 $ 35,769 $ 340,709 Nine Months Ended September 30, 2023 September 30, 2022 (In thousands) Network Solutions Services & Support Total Network Solutions Services & Support Total Optical Networking Solutions $ 342,390 $ 64,562 $ 406,952 $ 103,011 $ 15,834 $ 118,845 Access & Aggregation Solutions 254,868 39,315 294,183 243,396 34,877 278,273 Subscriber Solutions 196,726 25,760 222,486 252,899 17,248 270,147 Total $ 793,984 $ 129,637 $ 923,621 $ 599,306 $ 67,959 $ 667,265 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) 2023 2022 2023 2022 Optical Networking Solutions $ 116,200 $ 118,845 $ 406,952 $ 118,845 Access & Aggregation Solutions 94,646 88,189 294,183 278,273 Subscriber Solutions 61,485 133,675 222,486 270,147 Total $ 272,331 $ 340,709 $ 923,621 $ 667,265
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) 2023 2022 2023 2022 United States $ 111,494 $ 169,669 $ 375,254 $ 374,470 Germany 60,347 64,234 212,171 71,945 United Kingdom 41,242 46,569 150,710 123,477 Other international 59,248 60,237 185,486 97,373 Total $ 272,331 $ 340,709 $ 923,621 $ 667,265

Liability for Warranty Returns

Liability for Warranty Returns (Tables)	9 Months Ended
	Sep. 30, 2023
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, 2023 and 2022 are summarized as follows: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2023 2022 2023 2022 Balance at beginning of period $ 6,831 $ 4,842 $ 7,196 $ 5,403 Plus: Adtran Networks acquisition — 3,756 — 3,756 Plus: Amounts charged to cost and expenses 752 616 2,289 1,727 Plus: Foreign currency translation adjustments ( 73 ) — ( 33 ) — Less: Deductions ( 943 ) ( 613 ) ( 2,885 ) ( 2,285 ) Balance at end of period $ 6,567 $ 8,601 $ 6,567 $ 8,601

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2023
Restructuring and Related Activities [Abstract]
Schedule of Reconciliation of Restructuring Liabilities	A reconciliation of the beginning and ending restructuring liabilities, which is included in accrued wages and benefits in the Condensed Consolidated Balance Sheets as of September 30, 2023 and December 31, 2022, is as follows: Three Months Ended Nine Months Ended (In thousands) September 30, 2023 September 30, 2023 Balance at beginning of period $ 6,452 $ 159 Plus: Amounts charged to cost and expense 3,830 12,135 Less: Amounts paid ( 4,729 ) ( 6,741 ) Balance as of September 30, 2023 $ 5,553 $ 5,553 For the Year Ended (In thousands) December 31, 2022 Balance as of December 31, 2021 $ 1,514 Plus: Amounts charged to cost and expense 1,629 Less: Amounts paid ( 2,984 ) Balance as of December 31, 2022 $ 159
Schedule of Components of Restructuring Expenses	Restructuring expenses included in the Condensed Consolidated Statements of Loss are for the three and nine months ended September 30, 2023 and 2022: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2023 2022 2023 2022 Network Solutions - Cost of revenue $ 611 $ — $ 669 $ — Network Solutions - Inventory write down 21,043 — 21,043 — Services & Support - Cost of revenue ( 24 ) — ( 6 ) — Cost of revenue $ 21,630 $ — $ 21,706 $ — Selling, general and administrative expenses 3,387 — 6,960 2 Research and development expenses ( 144 ) — 4,512 — Total restructuring expenses $ 24,873 $ — $ 33,178 $ 2 The following table represents the components of restructuring expenses by geographic area for the three and nine months ended September 30, 2023 and 2022: Three Months Ended Nine Months Ended September 30, September 30, (In thousands) 2023 2022 2023 2022 United States $ 22,598 $ — $ 25,217 $ 2 International 2,275 — 7,961 — Total restructuring expenses $ 24,873 $ — $ 33,178 $ 2

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) € in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 EUR (€) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2023 EUR (€) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2023 USD ($)	Dec. 31, 2022	Oct. 18, 2022 shares	Jul. 18, 2022 USD ($)
Summary Of Significant Accounting Policy [Line Items]
Percentage of guaranteed interest rate	5%		5%		5%
Percentage of guaranteed interest rate plus a variable component	3.12%		3.12%		3.12%
Aggregate exit compensation payments obligation including guaranteed interest	€ 325,300		€ 325,300		$ 344,200
Expire date of exit compensation			Mar. 16, 2023	Mar. 16, 2023
Annual recurring compensation obligation			€ 10,600	$ 11,200
Accrued annual recurring compensation obligation | $		$ 2,900		$ 8,600
Number of shares tendered	1,000	1,000	64,000	64,000
Exit compensation payments	€ 8	$ 9	€ 1,100	$ 1,200
ASU 2021-08 [Member]
Summary Of Significant Accounting Policy [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true		true		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jul. 01, 2022		Jul. 01, 2022		Jul. 01, 2022
Administrative Agent [Member]
Summary Of Significant Accounting Policy [Line Items]
Credit agreement maximum borrowing capacity | $								$ 100,000
Credit agreement current borrowing capacity | $								$ 400,000
Adtran Networks SE [Member]
Summary Of Significant Accounting Policy [Line Items]
Number of shares tendered			64,000	64,000
Exit compensation payments	€ 8	$ 9	€ 1,100	$ 1,200
Equity method ownership percentage	34.60%		34.60%		34.60%	34.70%
Adtran Networks SE [Member] | Maximum [Member]
Summary Of Significant Accounting Policy [Line Items]
Number of additional shares authorized to purchase							15,346,544
Number of shares tendered	1,000	1,000

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 $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) $ / shares shares	Aug. 30, 2021 € / shares shares
Business Acquisition [Line Items]
Common stock, par value | $ / shares			$ 0.01	$ 0.01		$ 0.01		$ 0.01
Common stock, shares outstanding | shares				78,391,000		78,391,000		77,889,000
Common stock, reserved for future issuance | shares		27,994,595
Goodwill				$ 339,083		$ 339,083		$ 381,724
Total Revenue				272,331	$ 340,709	923,621	$ 667,265
Net Income (Loss)				(72,735)	(41,934)	(140,533)	(40,918)
Net loss attributable to non-controlling interest	[1]			(2,914)	(2,925)	(11,784)	(2,925)
Decrease in goodwill		$ 8,700
Network Solutions [Member]
Business Acquisition [Line Items]
Goodwill				294,407		294,407		298,280
Total Revenue				228,564	304,940	793,984	599,306
Services & Support [Member]
Business Acquisition [Line Items]
Goodwill				44,676		44,676		$ 83,444
Total Revenue				43,767	35,769	129,637	67,959
Common Stock [Member]
Business Acquisition [Line Items]
Percentage of common stock exchanged			64%
Adtran Networks SE [Member]
Business Acquisition [Line Items]
Business combination date of agreement			Aug. 30, 2021
Common stock, shares outstanding | shares		33,957,538
Percentage of outstanding bearer shares		65.43%	65.43%
Fair value of stock options assumed		$ 12,800
Goodwill		350,458		350,500		350,500
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
Total Revenue				158,400		537,500
Net Income (Loss)				38,800		79,400
Net loss attributable to non-controlling interest				0		3,200
Accrued annual recurring cash compensation non-controlling shareholders				2,900		8,600
Shares held by noncontrolling interest | shares			17,941,496						17,941,496
Closing share price | (per share)		$ 20.2	$ 17.64						€ 17.58
Currency conversion rate		1.00318
Adtran Networks SE [Member] | Selling, General and Administrative Expense [Member]
Business Acquisition [Line Items]
Transaction costs incurred						26,200
Transaction costs related to the business combination				$ 8	$ 10,600	$ 100	$ 13,300
Adtran Networks SE [Member] | Network Solutions [Member]
Business Acquisition [Line Items]
Goodwill		$ 272,800
Adtran Networks SE [Member] | Services & Support [Member]
Business Acquisition [Line Items]
Goodwill		$ 77,700
Adtran Networks 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%
[1] (1)For the three and nine months ended September 30, 2023, we have recog nized $ 2.9 million and $ 8.6 mi llion, respectively, representing the recurring cash compensation earned by non-controlling interest shareholders post-DPLTA and an incremen tal $ 3.2 millio n net loss attributable to non-controlling interests pre-DPLTA for the nine months ended September 30, 2023.

Business Combination - Summary

Business Combination - Summary of Purchase Price for Business Combination (Details) - Adtran Networks 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]
Adtran Networks 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)	$ 20.2	$ 17.64	€ 17.58
Purchase price paid for Adtran Networks 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, 2023	Dec. 31, 2022	Jul. 15, 2022
Net Assets:
Goodwill	$ 339,083	$ 381,724
Adtran Networks 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			200,331
Prepaid expenses and other current assets			28,208
Property plant and equipment			55,480
Deferred tax assets			1,759
Intangibles			403,780
Other non-current assets			31,074
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, net			(4,898)
Tax liabilities			(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			(61,040)
Total net assets acquired			544,217
Goodwill	$ 350,500		$ 350,458

Business Combination - Summar_3

Business Combination - Summary of Fair Value of Intangible Assets Acquired (Details) - Adtran Networks SE [Member] $ in Thousands	Jul. 15, 2022 USD ($)
Business Acquisition [Line Items]
Fair value	$ 403,780
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	$ 291,925
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, 2022
Business Combinations [Abstract]
Revenue	$ 368,192	$ 1,053,510
Net loss	$ (48,084)	$ (60,494)

Cash, Cash Equivalents and Rest

Cash, Cash Equivalents and Restricted Cash - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 116,092	$ 108,644

Revenue - Additional Informatio

Revenue - Additional Information (Detail)		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Category	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)
Revenue [Line Items]
Number of categories | Category				3
Accounts receivable, net		$ 229,333,000		$ 229,333,000			$ 279,435,000
Accounts receivable, allowance for credit losses		15,000		15,000			49,000
Allowance for credit losses related to contract assets		0	$ 0
Contract assets	[1]	888,000		888,000			1,852,000
Recognized revenue		6,100,000	$ 2,800,000	31,300,000	$ 12,300,000	$ 17,700,000
Factor [Member] | Purchase Agreement [Member]
Revenue [Line Items]
Accounts receivable sold		17,800,000		17,800,000			14,900,000
Factor [Member] | Purchase Agreement [Member] | Interest expense [Member]
Revenue [Line Items]
Cost of receivables		300,000		900,000
Factor [Member] | Purchase Agreement [Member] | Maximum [Member]
Revenue [Line Items]
Accounts receivable, allowance for credit losses		100,000		100,000			100,000
Factor [Member] | Purchase Agreement [Member] | Other Assets [Member]
Revenue [Line Items]
Accounts receivable gross		1,400,000		1,400,000
Contractual Maintenance Agreements, Contractual SaaS and Subscription Services and Hardware Orders [Member]
Revenue [Line Items]
Remaining performance obligations		$ 314,000,000		$ 314,000,000			$ 277,200,000
[1] Included in other receivables on the Condensed Consolidated Balance Sheets.

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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation Of Revenue [Line Items]
Revenue	$ 272,331	$ 340,709	$ 923,621	$ 667,265
Optical Networking Solutions
Disaggregation Of Revenue [Line Items]
Revenue	116,200	118,845	406,952	118,845
Access & Aggregation Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	94,646	88,189	294,183	278,273
Subscriber Solutions
Disaggregation Of Revenue [Line Items]
Revenue	61,485	133,675	222,486	270,147
Network Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	228,564	304,940	793,984	599,306
Network Solutions [Member] | Optical Networking Solutions
Disaggregation Of Revenue [Line Items]
Revenue	94,592	103,011	342,390	103,011
Network Solutions [Member] | Access & Aggregation Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	81,051	76,591	254,868	243,396
Network Solutions [Member] | Subscriber Solutions
Disaggregation Of Revenue [Line Items]
Revenue	52,921	125,338	196,726	252,899
Services & Support [Member]
Disaggregation Of Revenue [Line Items]
Revenue	43,767	35,769	129,637	67,959
Services & Support [Member] | Optical Networking Solutions
Disaggregation Of Revenue [Line Items]
Revenue	21,608	15,834	64,562	15,834
Services & Support [Member] | Access & Aggregation Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	13,595	11,598	39,315	34,877
Services & Support [Member] | Subscriber Solutions
Disaggregation Of Revenue [Line Items]
Revenue	$ 8,564	$ 8,337	$ 25,760	$ 17,248

Revenue - Additional Informat_2

Revenue - Additional Information (Detail1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-10-01	Sep. 30, 2023
Revenue [Line Items]
Remaining performance obligations, percentage	68.60%
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, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Accounts receivable, net		$ 229,333	$ 279,435
Contract assets	[1]	888	1,852
Unearned revenue		49,832	41,193
Non-current unearned revenue		$ 23,501	$ 19,239
[1] Included in other receivables on the Condensed Consolidated Balance Sheets.

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Income Tax Disclosure [Line Items]
Effective tax rate expense (benefit)	(18.00%)		(8.80%)	(19.20%)	(9.40%)
Deferred tax assets	$ 57,299			$ 57,299		$ 11,411
Valuation allowance established against deferred tax assets	5,016			5,016		$ 5,201
Net deferred tax assets	52,300			52,300
IRS [Member]
Income Tax Disclosure [Line Items]
Reversal of Income tax refund receivable	15,200			15,200
Reversal of research and development carry-forwards	$ 1,800			$ 1,800
Offsetting of uncertain tax position reserves		$ 17,000

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, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets	$ 57,299	$ 11,411
Valuation Allowance	(5,016)	(5,201)
Deferred Tax Assets, net	52,300
Net Deferred Tax Assets (Liabilities)	52,283	6,210
Domestic [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets	84,274	61,726
Valuation Allowance	(3,177)	(3,177)
Deferred Tax Assets, net	81,097	58,549
International [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Liabilities	(26,975)	(50,315)
Valuation Allowance	(1,839)	(2,024)
Deferred Tax Liabilities, net	$ (28,814)	$ (52,339)

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, 2023 $ / shares shares
Share-Based Payment Arrangement [Abstract]
Number of Shares, Unvested RSUs and restricted stock outstanding, beginning balance | shares	1,086
Number of Shares, RSUs and restricted stock granted | shares	1,484
Number of Shares, RSUs and restricted stock vested | shares	(56)
Number of Shares, RSUs and restricted stock forfeited | shares	(51)
Number of Shares, Unvested RSUs and restricted stock outstanding, ending balance | shares	2,463
Weighted Avg. Grant Date Fair Value, Unvested RSUs and restricted stock outstanding, Beginning Balance | $ / shares	$ 17.54
Weighted Avg. Grant Date Fair Value, RSUs and restricted stock granted | $ / shares	16.58
Weighted Avg. Grant Date Fair Value, RSUs and restricted stock vested | $ / shares	20.37
Weighted Avg. Grant Date Fair Value, RSUs and restricted stock forfeited | $ / shares	16.42
Weighted Avg. Grant Date Fair Value, Unvested RSUs and restricted stock outstanding, Ending Balance | $ / shares	$ 17.01

Stock-Based Compensation (PSUs,

Stock-Based Compensation (PSUs, RSUs and Restricted Stock) - Additional Information (Detail) shares in Thousands, $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share granted	1,484
Recognition period of unvested compensation expense	1 year 10 months 24 days
Options available for issuance under stockholders-approved equity plan	2,000
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options available for issuance under stockholders-approved equity plan	2,300
Performance Stock Units (PSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Recognition period of unvested compensation expense	2 years 3 months 18 days
Performance Stock Units (PSUs) [Member] | Executive Officers and Certain Employees [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share granted	900
Performance Stock Units (PSUs) [Member] | Executive Officers and Certain Employees [Member] | Tranche One [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of performance stock units granted	100%
Performance Stock Units (PSUs) [Member] | Executive Officers and Certain Employees [Member] | Tranche Two [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Performance Stock Units (PSUs) [Member] | Minimum [Member] | Executive Officers and Certain Employees [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of performance stock units granted	0%
Performance Stock Units (PSUs) [Member] | Minimum [Member] | Executive Officers and Certain Employees [Member] | Tranche One [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	2 years
Performance Stock Units (PSUs) [Member] | Maximum [Member] | Executive Officers and Certain Employees [Member] | Tranche Two [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of performance stock units granted	150%
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 | $	$ 19.1
Recognition period of unvested compensation expense	2 years 2 months 12 days
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to other than options | $	$ 11.3

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Options Outstanding (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Stock Options, Stock options outstanding, Beginning Balance | shares	3,148
Number of Stock Options, Stock options granted | shares	7
Number of Stock Options, Stock options exercised | shares	(8)
Number of Stock Options, Stock options forfeited | shares	(40)
Number of Stock Options, Stock options expired | shares	(33)
Number of Stock Options, Stock options outstanding, Ending Balance | shares	3,074	3,148
Number of Stock Options, Stock options exercisable | shares	1,691
Weighted Avg. Exercise Price, Stock options outstanding, Beginning Balance | $ / shares	$ 14.37
Weighted Avg. Exercise Price, Stock options granted | $ / shares	12.17
Weighted Avg. Exercise Price, Stock options exercised | $ / shares	8.72
Weighted Avg. Exercise Price, Stock options forfeited | $ / shares	11.93
Weighted Avg. Exercise Price, Stock options expired | $ / shares	16.44
Weighted Avg. Exercise Price, Stock options outstanding, Ending Balance | $ / shares	14.39	$ 14.37
Weighted Avg. Exercise Price, Stock options exercisable | $ / shares	$ 15.88
Weighted Avg. Remaining Contractual Life In Years, Stock options outstanding	2 years 8 months 4 days	3 years 5 months 1 day
Weighted Avg. Remaining Contractual Life in Years, Stock options exercisable	1 year 2 months 23 days
Aggregate Intrinsic Value, Stock options outstanding | $	$ 16,251
Aggregate Intrinsic Value, Stock options outstanding | $	736	$ 16,251
Aggregate Intrinsic Value, Stock options exercisable | $	$ 556
Adtran Networks SE [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Stock Options, Stock options outstanding, Beginning Balance | shares	81
Number of Stock Options, Stock options exercised | shares	(13)
Number of Stock Options, Stock options forfeited | shares	(9)
Number of Stock Options, Stock options expired | shares	(1)
Number of Stock Options, Stock options outstanding, Ending Balance | shares	58	81
Number of Stock Options, Stock options exercisable | shares	12
Weighted Avg. Exercise Price, Stock options outstanding, Beginning Balance | $ / shares	$ 8.58
Weighted Avg. Exercise Price, Stock options exercised | $ / shares	8.22
Weighted Avg. Exercise Price, Stock options forfeited | $ / shares	10.58
Weighted Avg. Exercise Price, Stock options expired | $ / shares	9.2
Weighted Avg. Exercise Price, Stock options outstanding, Ending Balance | $ / shares	8.18	$ 8.58
Weighted Avg. Exercise Price, Stock options exercisable | $ / shares	$ 6.03
Weighted Avg. Remaining Contractual Life In Years, Stock options outstanding	3 years 4 months 20 days	4 years
Weighted Avg. Remaining Contractual Life in Years, Stock options exercisable	1 year 5 months 23 days
Aggregate Intrinsic Value, Stock options outstanding | $	$ 1,222
Aggregate Intrinsic Value, Stock options outstanding | $	746	$ 1,222
Aggregate Intrinsic Value, Stock options exercisable | $	$ 182

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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Jul. 22, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation expense	$ 4,200	$ 12,100	$ 12,200	$ 15,900
Unrecognized compensation expense related to stock options	$ 5,200		$ 5,200
Recognition period of unvested compensation expense			1 year 10 months 24 days
Options available for issuance under stockholders-approved equity plan	2		2
Aggregate intrinsic value based on fair market value	$ 736		$ 736		$ 16,251
Total pre-tax intrinsic value of options exercised			$ 50
Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options available for issuance under stockholders-approved equity plan	2.3		2.3
Adtran Networks SE [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation expense related to stock options	$ 100		$ 100
Recognition period of unvested compensation expense			3 years 4 months 24 days
Options available for issuance under stockholders-approved equity plan						2.1
Aggregate intrinsic value based on fair market value	$ 746		$ 746		$ 1,222
Total pre-tax intrinsic value of options exercised			$ 200

Investments - Debt Securities a

Investments - Debt Securities and Other Investments, Included on Condensed Consolidated Balance Sheet and Recorded at Fair Value (Detail) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		$ 9,671,000
Gross Unrealized Gains		9,000
Gross Unrealized Losses		(427,000)
Fair Value	$ 0	9,253,000
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,538,000
Gross Unrealized Gains		5,000
Gross Unrealized Losses		(81,000)
Fair Value		2,462,000
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		185,000
Gross Unrealized Losses		(5,000)
Fair Value		180,000
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		818,000
Gross Unrealized Gains		1,000
Gross Unrealized Losses		(24,000)
Fair Value		795,000
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		1,853,000
Gross Unrealized Losses		(105,000)
Fair Value		1,748,000
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		3,870,000
Gross Unrealized Gains		3,000
Gross Unrealized Losses		(188,000)
Fair Value		3,685,000
Foreign Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		407,000
Gross Unrealized Losses		(24,000)
Fair Value		$ 383,000

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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Gross realized gain on debt securities	$ 5	$ 1	$ 9	$ 14
Gross realized loss on debt securities	(317)	(116)	(355)	(242)
Total loss recognized, net	$ (312)	$ (115)	$ (346)	$ (228)

Investments - Additional Inform

Investments - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Schedule of Investments [Line Items]
Available-for-sale debt securities, allowance for credit losses	$ 0		$ 0
Purchase an available-for-sale debt securities with credit deterioration	0
Available-for-sale debt securities	0	$ 9,253,000
Other investments	$ 0
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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Unrealized gain (loss) on equity securities held	$ (1,130)	$ (1,217)	$ 1,404	$ (8,849)
Realized gain (loss) on equity securities sold	(1)	(1,358)	13	(1,675)
Total gain (loss) recognized, net	$ (1,131)	$ (2,575)	$ 1,417	$ (10,524)

Investments - Cash Equivalents

Investments - Cash Equivalents and Investments held at Fair Value (Detail) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities	$ 0	$ 9,253,000
Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	5,245,000	228,000
Total short-term and long-term investments	25,179,000	33,005,000
Total	30,424,000	33,233,000
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	5,245,000	228,000
Total short-term and long-term investments	25,179,000	27,437,000
Total	30,424,000	27,665,000
Fair Value, Measurements [Member] | Significant Other Observable Inputs (Level 2) [Member]
Schedule of Available-for-sale Securities [Line Items]
Total short-term and long-term investments		5,568,000
Total		5,568,000
Money Market Funds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash equivalents	5,245,000	228,000
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	5,245,000	228,000
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		2,462,000
Corporate Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		2,462,000
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		2,462,000
Municipal Fixed-Rate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		180,000
Municipal Fixed-Rate Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		180,000
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		180,000
Asset-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		795,000
Asset-Backed Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		795,000
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		795,000
Mortgage/Agency-Backed Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		1,748,000
Mortgage/Agency-Backed Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		1,748,000
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		1,748,000
U.S. Government Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		3,685,000
U.S. Government Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		3,685,000
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		3,685,000
Foreign Government Securities / Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		383,000
Foreign Government Securities / Bonds [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale debt securities		383,000
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		383,000
Marketable Equity Securities - Various Industries [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	815,000	810,000
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	815,000	810,000
Deferred Compensation Plan Assets [Member] | Fair Value, Measurements [Member]
Schedule of Available-for-sale Securities [Line Items]
Marketable equity securities	24,364,000	22,942,000
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	$ 24,364,000	$ 22,942,000

Inventory - Components of Inven

Inventory - Components of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
Raw materials	$ 156,287	$ 186,346
Work in process	15,648	12,087
Finished goods	202,036	229,098
Total Inventory, net	$ 373,971	$ 427,531

Inventory - Additional Informat

Inventory - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Inventory Disclosure [Abstract]
Inventory valuation reserves	$ 86,300		$ 86,300		$ 57,000
Inventory write down	$ 21,000	$ 0	$ 21,043	$ 0

Property, Plant and Equipment -

Property, Plant and Equipment - Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Engineering and other equipment	$ 179,049	$ 170,785
Building	85,966	82,932
Computer hardware and software	97,192	80,455
Building and land improvements	51,284	47,861
Furniture and fixtures	23,686	22,403
Land	5,325	5,364
Total property, plant and equipment	442,502	409,800
Less: accumulated depreciation	(323,879)	(299,101)
Total property, plant and equipment, net	$ 118,623	$ 110,699

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Asset impairments	$ 0	$ 16,969,000	$ 0	$ 16,969,000
Depreciation expense	$ 7,400,000	7,100,000	$ 22,600,000	12,600,000
ADVA Optical Networking SE [Member]
Property, Plant and Equipment [Line Items]
Asset impairments		$ 17,000,000		$ 17,000,000

Goodwill - Summary of Changes i

Goodwill - Summary of Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Goodwill [Line Items]
Goodwill, Beginning balance		$ 381,724
Goodwill impairment	$ (37,874)	(37,874)
Goodwill impairment		37,500
Foreign currency translation adjustments		(5,141)
Goodwill, Ending balance	339,083	339,083
Network Solutions [Member]
Goodwill [Line Items]
Goodwill, Beginning balance		298,280
Foreign currency translation adjustments		(3,873)
Goodwill, Ending balance	294,407	294,407
Services & Support [Member]
Goodwill [Line Items]
Goodwill, Beginning balance		83,444
Goodwill impairment	(37,900)
Goodwill impairment		37,500
Foreign currency translation adjustments		(1,268)
Goodwill, Ending balance	$ 44,676	$ 44,676

Goodwill - Additional Informati

Goodwill - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022	Jul. 15, 2022
Goodwill [Line Items]
Goodwill	$ 339,083	$ 339,083	$ 381,724
Impairment of goodwill	37,874	37,874
Services & Support [Member]
Goodwill [Line Items]
Goodwill	44,676	$ 44,676	$ 83,444
Impairment of goodwill	$ 37,900
Adtran Networks SE [Member]
Goodwill [Line Items]
Goodwill				$ 350,500

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 459,768	$ 467,689
Accumulated Amortization	(131,073)	(66,478)
Net Book Value	$ 328,695	401,211
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	10 years 10 months 24 days
Gross Carrying Amount	$ 53,247	55,517
Accumulated Amortization	(14,490)	(12,772)
Net Book Value	$ 38,757	42,745
Backlog [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	1 year 7 months 6 days
Gross Carrying Amount	$ 55,017	55,782
Accumulated Amortization	(49,061)	(22,725)
Net Book Value	$ 5,956	33,057
Developed Technology [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	8 years 6 months
Gross Carrying Amount	$ 316,083	320,364
Accumulated Amortization	(49,944)	(21,856)
Net Book Value	$ 266,139	298,508
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	(3,633)	(3,141)
Net Book Value	$ 2,267	2,759
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	(353)	(298)
Net Book Value	$ 207	262
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	(483)	(431)
Net Book Value	$ 17	69
Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Useful Life (in years)	3 years
Gross Carrying Amount	$ 28,461	29,066
Accumulated Amortization	(13,109)	(5,255)
Net Book Value	$ 15,352	$ 23,811

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Acquired Finite-Lived Intangible Assets [Line Items]
Impairment losses of intangible assets	$ 0	$ 0	$ 0	$ 0
Amortization expense	$ 16,500,000	$ 20,400,000	$ 68,800,000	$ 22,200,000

Intangible Assets - Estimated F

Intangible Assets - Estimated Future Amortization Expense Related to Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2023	$ 13,770
2024	56,800
2025	45,504
2026	42,290
2027	40,941
Thereafter	129,390
Net Book Value	$ 328,695	$ 401,211

Hedging - Additional Informatio

Hedging - Additional Information (Detail) € in Millions	9 Months Ended
	Sep. 30, 2023 EUR (€) ForwardContracts	Mar. 21, 2023 EUR (€)	Nov. 03, 2022 EUR (€)
Foreign Exchange Forward [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of forward rate contracts outstanding | ForwardContracts	49
Cross-Currency Swap Arrangement [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Aggregate notional amount		€ 160	€ 160
Forward contract tranche settled on hedge	€ 20
Cross-Currency Swap Arrangement [Member] | Eight Quarterly Tranches [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Aggregate notional amount			€ 20
Cross-Currency Swap Arrangement [Member] | Five Quarterly Tranches [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Aggregate notional amount	€ 20	€ 20
Cross-Currency Swap Arrangement [Member] | Minimum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Aggregate notional amount, daily fixed forward conversion rate		1.085	0.98286
Cross-Currency Swap Arrangement [Member] | Maximum [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Aggregate notional amount, daily fixed forward conversion rate		1	1.0329

Hedging - Schedule of Fair Valu

Hedging - Schedule of Fair Values of Derivative Instruments (Detail) - Derivatives Not Designated as Hedging Instruments [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Other income , net [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Foreign exchange contracts	$ 1,012	$ 1,076
Level 2 [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Total derivatives	7,520	7,520	$ 11,359
Level 2 [Member] | Other Receivables [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Foreign exchange contracts - derivative assets	7,530	7,530	11,992
Level 2 [Member] | Accounts Payable [Member]
Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Foreign exchange contracts - derivative liabilities	$ (10)	$ (10)	$ (633)

Revolving Credit Agreements - C

Revolving Credit Agreements - Carrying Amount of Current and Non-Current Revolving Agreements (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Total current revolving credit agreements	$ 10,580	$ 35,936
Total non-current revolving credit agreement	200,000	60,000
New Nord/LB Revolving Line of Credit [Member]
Line of Credit Facility [Line Items]
Total current revolving credit agreements	10,580
Nord/LB Revolving Line of Credit [Member]
Line of Credit Facility [Line Items]
Total current revolving credit agreements		16,091
Syndicated Credit Agreement Working Capital Line of Credit [Member]
Line of Credit Facility [Line Items]
Total current revolving credit agreements		10,727
DZ Bank Revolving Line of Credit [Member]
Line of Credit Facility [Line Items]
Total current revolving credit agreements		9,118
Wells Fargo Credit Agreement [Member]
Line of Credit Facility [Line Items]
Total non-current revolving credit agreement	$ 200,000	$ 60,000

Revolving Credit Agreements - A

Revolving Credit Agreements - Additional Information (Detail) - USD ($)				9 Months Ended
	Aug. 09, 2023	Mar. 29, 2023	Aug. 08, 2022	Sep. 30, 2023	Dec. 31, 2022	Jul. 18, 2022	Sep. 30, 2018
Line Of Credit Facility [Line Items]
Weighted average interest rate				7.11%
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				2.65%
Maximum [Member] | Base Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				1.65%
Maximum [Member] | EURIBOR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				2.75%
Minimum [Member] | Daily Simple SOFR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				1.65%
Minimum [Member] | Base Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				0.65%
Minimum [Member] | EURIBOR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				1.75%
Wells Fargo Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Net leverage ratio	3
Wells Fargo Credit Agreement [Member] | DDTL Interest Rate [Member]
Line Of Credit Facility [Line Items]
Debt instrument default interest rate percentage				2%
Commitment fee percentage				0.25%
Wells Fargo Credit Agreement [Member] | Daily Simple SOFR [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				1%
Wells Fargo Credit Agreement [Member] | Daily Simple SOFR [Member] | DDTL Interest Rate [Member]
Line Of Credit Facility [Line Items]
Credit facility, floor rate				0%
Applicable margin rate				1%
Wells Fargo Credit Agreement [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Commitment fee percentage				0.25%
Wells Fargo Credit Agreement [Member] | Maximum [Member] | Daily Simple SOFR [Member] | DDTL Interest Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				2.90%
Wells Fargo Credit Agreement [Member] | Maximum [Member] | Base Rate [Member] | DDTL Interest Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				1.90%
Wells Fargo Credit Agreement [Member] | Minimum [Member]
Line Of Credit Facility [Line Items]
Commitment fee percentage				0.20%
Wells Fargo Credit Agreement [Member] | Minimum [Member] | Daily Simple SOFR [Member] | DDTL Interest Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				1.90%
Wells Fargo Credit Agreement [Member] | Minimum [Member] | Base Rate [Member] | DDTL Interest Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				0.90%
Wells Fargo Credit Agreement [Member] | Federal Reserve Bank Advances [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				1%
Wells Fargo Credit Agreement [Member] | Federal Reserve Bank Advances [Member] | DDTL Interest Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate				1%
Wells Fargo Credit Agreement Amendment [Member]
Line Of Credit Facility [Line Items]
Secured revolving credit facility amount	$ 50,000,000
External debt capped basket amount amended	30,000,000
Aggregate principal amount	$ 172,500,000
Wells Fargo Credit Agreement Amendment [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Net leverage ratio	5
Wells Fargo Credit Agreement Amendment [Member] | Minimum [Member]
Line Of Credit Facility [Line Items]
Net leverage ratio	3.25
Wells Fargo Credit Agreement Amendment [Member] | Delayed Draw Term Loan [Member]
Line Of Credit Facility [Line Items]
Revolving line of credit	$ 50,000,000
Percentage available for borrowing	60%
Nord/LB Revolving Line of Credit [Member]
Line Of Credit Facility [Line Items]
Revolving line of credit		$ 16,100,000		$ 10,600,000
Nord/LB Revolving Line of Credit [Member] | Euro Short Term Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate		1.94%
Prior Nord/Lb Revolving Line Of Credit [Member]
Line Of Credit Facility [Line Items]
Revolving line of credit			$ 16,100,000
Available for future borrowings			$ 0
Line of credit maturity period month and year			2023-08
Prior Nord/Lb Revolving Line Of Credit [Member] | Euro Short Term Rate [Member]
Line Of Credit Facility [Line Items]
Applicable margin rate			1.40%
DZ Bank Revolving Line Of Credit [Member]
Line Of Credit Facility [Line Items]
Revolving line of credit					$ 9,100,000
Available for future borrowings					$ 0
Interest rate					2.80%
Syndicated Credit Agreement Working Capital Line of Credit [Member]
Line Of Credit Facility [Line Items]
Available for future borrowings							$ 0
Acorn HoldCo, Inc., [Member] | Wells Fargo Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Secured revolving credit facility amount				400,000,000		$ 100,000,000
Revolving line of credit				200,000,000
Credit facility, average outstanding amount				2,200,000
Letters of credit may be issued				25,000,000
Available for future borrowings				$ 197,800,000
Acorn HoldCo, Inc., [Member] | Wells Fargo Credit Agreement [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Credit agreement current borrowing capacity						$ 400,000,000
Bayerische Landesbank and Deutsche Bank [Member] | Syndicated Credit Agreement Working Capital Line of Credit [Member]
Line Of Credit Facility [Line Items]
Secured revolving credit facility amount							$ 10,700,000
First Quarter Ending Springing Covenant Period [Member] | Wells Fargo Credit Agreement Amendment [Member]
Line Of Credit Facility [Line Items]
Net leverage ratio	4
Second Quarter Ending Springing Covenant Event [Member] | Wells Fargo Credit Agreement Amendment [Member]
Line Of Credit Facility [Line Items]
Net leverage ratio	3.75
Third and Fourth Quarters Ending Springing Covenant Event [Member] | Wells Fargo Credit Agreement Amendment [Member]
Line Of Credit Facility [Line Items]
Net leverage ratio	3.5
Springing Covenant Event [Member] | Wells Fargo Credit Agreement Amendment [Member]
Line Of Credit Facility [Line Items]
Net leverage ratio	3.5

Notes Payable - Carrying Amount

Notes Payable - Carrying Amounts of Note Payables (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Debt Instrument [Line Items]
Carrying Value	$ 24,598
Syndicated Credit Agreement Notes Payable [Member]
Debt Instrument [Line Items]
Carrying Value	$ 24,598

Notes Payable - Additional Info

Notes Payable - Additional Information (Details) - Syndicated Credit Agreement Notes Payable [Member] - USD ($)	Jan. 31, 2023	Sep. 30, 2018
Debt Instrument [Line Items]
Available for future borrowings	$ 0
Bayerische Landesbank and Deutsche Bank [Member]
Debt Instrument [Line Items]
Notes payable borrowings		$ 63,700,000

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Pension liability	$ 10,732		$ 10,624
Contributions to defined benefit pension plans	2,800	$ 1,200
Defined benefit pension plans for the remainder of fiscal year	900
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Business combination, acquired additional obligation	29,600
Business combination, acquired assets	$ 22,300

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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 401	$ 478	$ 1,203	$ 981
Interest cost	$ (33)	$ 204	$ (99)	$ 638
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Expected return on plan assets	$ 59	$ (465)	$ 177	$ (1,384)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Amortization of actuarial losses	$ 7	$ 81	$ 20	$ 254
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Net periodic benefit cost	$ 434	$ 298	$ 1,300	$ 489

Equity - Changes in Accumulated

Equity - Changes in Accumulated Other Comprehensive Income (Loss), Net of Tax, by Component (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 782,470	$ 348,537	$ 1,303,613	$ 357,102
Other comprehensive income (loss) before reclassifications	(29,081)	(23,426)	(13,365)	(28,748)
Amounts reclassified from accumulated other comprehensive income (loss)	(327)	(260)	(304)	280
Net current period other comprehensive income (loss)	(29,408)	(23,686)	(13,669)	(28,468)
Less: Comprehensive income (loss) attributable to non-controlling interest, net of tax		(94)	244	(94)
Ending Balance	684,893	1,184,827	684,893	1,184,827
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 Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	62,208	(16,696)	46,713	(11,914)
Ending Balance	32,800	(40,288)	32,800	(40,288)
Unrealized (Losses) Gains on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(773)	(1,476)	(836)	(552)
Other comprehensive income (loss) before reclassifications	635	(254)	733	(1,818)
Amounts reclassified from accumulated other comprehensive income (loss)	(244)	(142)	(279)	498
Net current period other comprehensive income (loss)	391	(396)	454	(1,320)
Ending Balance	(382)	(1,872)	(382)	(1,872)
Defined Benefit Plan Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(958)	(5,713)	(1,016)	(5,613)
Amounts reclassified from accumulated other comprehensive income (loss)	(83)	(118)	(25)	(218)
Net current period other comprehensive income (loss)	(83)	(118)	(25)	(218)
Ending Balance	(1,041)	(5,831)	(1,041)	(5,831)
Foreign Currency Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	63,554	(9,892)	48,180	(6,134)
Other comprehensive income (loss) before reclassifications	(29,716)	(23,172)	(14,098)	(26,930)
Net current period other comprehensive income (loss)	(29,716)	(23,172)	(14,098)	(26,930)
Less: Comprehensive income (loss) attributable to non-controlling interest, net of tax		(94)	244	(94)
Ending Balance	$ 33,838	$ (32,970)	$ 33,838	$ (32,970)

Equity - Reclassifications Out

Equity - Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss Before Income Taxes	$ (92,202)	$ (49,171)	$ (188,546)	$ (48,415)
Tax benefit	16,553	4,312	36,229	4,572
Net Loss attributable to ADTRAN Holdings, Inc.	(72,735)	(41,934)	(140,533)	(40,918)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Loss Before Income Taxes	441	358	403	(339)
Tax benefit	(114)	(98)	(99)	59
Net Loss attributable to ADTRAN Holdings, Inc.	327	260	304	(280)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member] | Unrealized (Losses) Gains on Available-for-Sale Securities [Member]
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net investment (loss) gain	321	187	367	(655)
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 loss	$ 120	$ 171	$ 36	$ 316

Equity - Tax Effects Related to

Equity - Tax Effects Related to the Change in Each Component of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Equity [Abstract]
Unrealized gain (loss) on available-for-sale securities, Before-Tax Amount	$ 836			$ (334)			$ 964	$ (2,392)
Unrealized gain (loss) on available-for-sale securities, Tax (Expense) Benefit	(201)			80			(231)	574
Unrealized gain (loss) on available-for-sale securities, Net-of-Tax Amount	635			(254)			733	(1,818)
Reclassification adjustment for amounts related to available-for-sale investments included in net (loss) gain, Before-Tax Amount	(321)			(187)			(367)	655
Reclassification adjustment for amounts related to available-for-sale investments included in net (loss) gain, Tax (Expense) Benefit	77			45			88	(157)
Reclassification adjustment for amounts related to available-for-sale investments included in net (loss) gain, Net-of-Tax Amount	(244)			(142)			(279)	498
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net gain (loss), Before-Tax Amount	(120)			(171)			(36)	(316)
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net gain (loss), Tax (Expense) Benefit	37			53			11	98
Reclassification adjustment for amounts related to defined benefit plan adjustments included in net gain (loss), Net-of-Tax Amount	(83)			(118)			(25)	(218)
Foreign currency translation adjustment, Before-Tax Amount	(29,716)			(23,172)			(14,098)	(26,930)
Foreign currency translation adjustment, Net-of-Tax Amount	(29,716)			(23,172)			(14,098)	(26,930)
Total Other Comprehensive Income (Loss), Before-Tax Amount	(29,321)			(23,864)			(13,537)	(28,983)
Total Other Comprehensive Income (Loss), Tax (Expense) Benefit	(87)			178			(132)	515
Other Comprehensive Loss, net of tax	$ (29,408)	$ 6,957	$ 8,782	$ (23,686)	$ (3,140)	$ (1,642)	$ (13,669)	$ (28,468)

Redeemable Non-controlling In_3

Redeemable Non-controlling Interest - Summary of Redeemable Non-controlling Interest Activity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Redeemable Noncontrolling Interest [Line Items]
Reclassification of non-controlling interests	$ 443,757
Redemption of redeemable non-controlling interest	(1,558)
Net income attributable to redeemable non-controlling interests	8,605
Annual recurring compensation earned	(8,605)
Translation adjustment	(10,291)
Balance as of March 31, 2023	431,921
Adtran Networks [Member]
Redeemable Noncontrolling Interest [Line Items]
Stock option exercises	$ 13

Redeemable Non-controlling In_4

Redeemable Non-controlling Interest Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Redeemable Noncontrolling Interest, Equity, Carrying Amount [Abstract]
Annual dividend recognized to redeemable non-controlling shareholders	$ 2.9	$ 8.6

Loss per share - Summary of Cal

Loss per share - Summary of Calculation of Basic and Diluted Loss Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator
Net loss attributable to ADTRAN Holdings, Inc.	$ (72,735)	$ (41,934)	$ (140,533)	$ (40,918)
Denominator
Weighted average number of shares – basic	78,389	73,036	78,378	57,175
Effect of dilutive securities
Weighted average number of shares – diluted	78,389	73,036	78,378	57,175
Loss per share attributable to ADTRAN Holdings, Inc. - basic	$ (0.93)	$ (0.57)	$ (1.79)	$ (0.72)
Loss per share attributable to ADTRAN Holdings, Inc. - diluted	$ (0.93)	$ (0.57)	$ (1.79)	$ (0.72)

Loss per share - Additional Inf

Loss per share - Additional Information (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive effect excluded calculation of diluted earnings per share	2,600	100	1,400	200
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	500	4	400	4

Segment Information - Additiona

Segment Information - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Segment Category	Sep. 30, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			2
Number of categories | Category			3
Depreciation expense	$ 7,400,000	$ 7,100,000	$ 22,600,000	$ 12,600,000
Network Solutions [Member]
Segment Reporting Information [Line Items]
Depreciation expense	1,500,000	1,100,000	4,500,000	1,600,000
Services And Support [Member]
Segment Reporting Information [Line Items]
Depreciation expense	$ 2,400	$ 2,400	$ 7,300	$ 8,000

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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Revenue	$ 272,331	$ 340,709	$ 923,621	$ 667,265
Gross Profit	74,237	103,027	254,598	219,849
Network Solutions [Member]
Segment Reporting Information [Line Items]
Revenue	228,564	304,940	793,984	599,306
Gross Profit	47,277	82,334	176,607	186,126
Services & Support [Member]
Segment Reporting Information [Line Items]
Revenue	43,767	35,769	129,637	67,959
Gross Profit	$ 26,960	$ 20,693	$ 77,991	$ 33,723

Segment Information - Revenue I

Segment Information - Revenue Information by Category (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation Of Revenue [Line Items]
Revenue	$ 272,331	$ 340,709	$ 923,621	$ 667,265
Optical Networking Solutions
Disaggregation Of Revenue [Line Items]
Revenue	116,200	118,845	406,952	118,845
Access & Aggregation Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	94,646	88,189	294,183	278,273
Subscriber Solutions [Member]
Disaggregation Of Revenue [Line Items]
Revenue	$ 61,485	$ 133,675	$ 222,486	$ 270,147

Segment Information - Revenue_2

Segment Information - Revenue Information by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue from External Customer [Line Items]
Revenue	$ 272,331	$ 340,709	$ 923,621	$ 667,265
United States [Member]
Revenue from External Customer [Line Items]
Revenue	111,494	169,669	375,254	374,470
Germany [Member]
Revenue from External Customer [Line Items]
Revenue	60,347	64,234	212,171	71,945
United Kingdom [Member]
Revenue from External Customer [Line Items]
Revenue	41,242	46,569	150,710	123,477
Other International [Member]
Revenue from External Customer [Line Items]
Revenue	$ 59,248	$ 60,237	$ 185,486	$ 97,373

Liability for Warranty Return_2

Liability for Warranty Returns - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Product Warranties Disclosures [Abstract]
Period of assurance-based warranty for product defects	90 days to five years
Liability for warranty obligations	$ 6,567	$ 6,831	$ 7,196	$ 8,601	$ 4,842	$ 5,403

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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Product Warranties Disclosures [Abstract]
Balance at beginning of period	$ 6,831	$ 4,842	$ 7,196	$ 5,403
Plus: Adtran Networks acquisition		3,756		3,756
Plus: Amounts charged to cost and expenses	752	616	2,289	1,727
Plus: Foreign currency translation adjustments	(73)	0	(33)	0
Less: Deductions	(943)	(613)	(2,885)	(2,285)
Balance at end of period	$ 6,567	$ 8,601	$ 6,567	$ 8,601

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) € in Thousands, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 EUR (€) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2023 EUR (€) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Aggregate exit compensation payments obligation including guaranteed interest	€ 325,300		€ 325,300		$ 344,200
Number of shares tendered | shares	1	1	64	64
Exit compensation payments	€ 8	$ 9	€ 1,100	$ 1,200
Percentage of guaranteed interest rate	5%		5%		5%
Percentage of guaranteed interest rate plus a variable component	3.12%		3.12%		3.12%
Expire date of exit compensation			Mar. 16, 2023	Mar. 16, 2023
Annual recurring compensation obligation			€ 10,600	$ 11,200
Accrued annual recurring compensation obligation		$ 2,900		$ 8,600
Commitments related to performance bonds					$ 11,800	$ 22,000
Commitments related to performance bonds expiration month and year			2031-04	2031-04
Purchase commitments					$ 308,400

Restructuring - Additional Info

Restructuring - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Restructuring Cost and Reserve [Line Items]
Inventory write down	$ 21,000	$ 0	$ 21,043	$ 0
Network Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Inventory write down	$ 21,000		$ 21,000

Restructuring - Schedule of Rec

Restructuring - Schedule of Reconciliation of Restructuring Liability (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Restructuring and Related Activities [Abstract]
Balance at beginning of period	$ 6,452	$ 159	$ 1,514
Plus: Amounts charged to cost and expense	3,830	12,135	1,629
Less: Amounts paid	(4,729)	(6,741)	(2,984)
Balance at end of period	$ 5,553	$ 5,553	$ 159

Restructuring - Schedule of Com

Restructuring - Schedule of Components of Restructuring Expenses Including in Condensed Consolidated Statements of (Loss) Income (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	$ 24,873	$ 33,178	$ 2
Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	21,630	21,706
Cost of Sales [Member] | Network Solutions [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	611	669
Cost of Sales [Member] | Services & Support [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	(24)	(6)
Inventory Write Down [Member] | Network Solutions [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	21,043	21,043
Selling, General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	3,387	6,960	$ 2
Research and Development Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	$ (144)	$ 4,512

Restructuring - Schedule of C_2

Restructuring - Schedule of Components of Restructuring Expense by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	$ 24,873	$ 33,178	$ 2
United States [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	22,598	25,217	$ 2
International [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses	$ 2,275	$ 7,961