Summary of Significant Accounting Policies - Summary of Impact of Restatement to Specific Line Items in Consolidated Statement of Changes in Stockholders Equity (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2024	Sep. 30, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				$ 605,257	$ 605,257	$ 605,257	$ 605,257	$ 1,303,613	$ 357,102
Net loss							(450,067)	(261,906)	(8,888)
Annual recurring compensation earned							(9,824)	(10,125)
Acquisition of Adtran Networks								3,762
Reclassification and remeasurement from equity to mezzanine equity for non-controlling interests in Adtran Networks								(443,757)
Mezzanine equity for non-controlling interest in adtran networks for adtran networks stock options exercised								(1,175)
Remeasurement of redeemable non-controlling interest							(1,175)
Other comprehensive income (loss), net of tax	$ (35,907)	$ 18,911	$ (1,449)	(17,833)	(19,282)	(369)	(36,276)	21,786	57,709
Dividend payments ($0.09 per share)								(21,237)	(22,885)
Dividends accrued on unvested restricted stock units								8	353
Deferred compensation adjustments, net of tax							259	(1,845)	(71)
ADTRAN RSUs and restricted stock vested							(1,022)	(1,106)	(9,847)
ADTRAN Stock options exercised							825	164	6,131
Modification of stock options							(190)	339
Redemption of redeemable non-controlling interest							2,986	371
ADTRAN Stock-based compensation expense							14,825	16,016	26,141
Ending Balance	126,951						126,951	605,257	1,303,613
Adtran Networks SE [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Acquisition of Adtran Networks									894,675
ADTRAN Stock options exercised									726
ADTRAN Stock-based compensation expense							1,353	26	2,181
Retained Deficit [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				(231,706)	(231,706)	(231,706)	(231,706)	55,338	740,820
Net loss							(450,067)	(258,727)	(2,037)
Annual recurring compensation earned							(9,824)	(10,125)
Acquisition of Adtran Networks								3,762
Dividend payments ($0.09 per share)								(21,237)	(22,885)
Dividends accrued on unvested restricted stock units								8	353
Deferred compensation adjustments, net of tax								(145)
ADTRAN RSUs and restricted stock vested							(1,026)	(1,115)	(10,482)
ADTRAN Stock options exercised							824	164	5,330
Redemption of redeemable non-controlling interest							2,986	371
Ending Balance	(688,813)						(688,813)	(231,706)	55,338
Accumulated Other Comprehensive Income [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				47,530	47,530	47,530	47,530	26,126	(11,914)
Other comprehensive income (loss), net of tax							(36,276)	21,404	38,040
Ending Balance	11,254						11,254	47,530	26,126
Additional Paid-In Capital [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				794,468	794,468	794,468	794,468	895,834	288,946
Mezzanine equity for non-controlling interest in adtran networks for adtran networks stock options exercised								(1,175)
Remeasurement of redeemable non-controlling interest							(1,175)
Deferred compensation adjustments, net of tax							(368)
Modification of stock options							(190)	339
ADTRAN Stock-based compensation expense							14,825	16,016	26,141
Ending Balance	808,913						808,913	794,468	895,834
Additional Paid-In Capital [Member] | Adtran Networks SE [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Acquisition of Adtran Networks									577,980
Reclassification and remeasurement from equity to mezzanine equity for non-controlling interests in Adtran Networks								(116,895)
ADTRAN Stock options exercised								323	472
ADTRAN Stock-based compensation expense							1,353	26	2,108
As Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				593,822	593,822	593,822	593,822
Annual recurring compensation earned			400	400
Other comprehensive income (loss), net of tax	(36,480)	19,097	(1,382)	(17,805)	(19,187)	(88)	(36,568)	21,717
Ending Balance	134,414						134,414	593,822
As Reported [Member] | Retained Deficit [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				(243,908)	(243,908)	(243,908)	(243,908)	55,338
Net loss							(441,048)	(256,164)
Annual recurring compensation earned							(9,824)	(11,524)
Dividend payments ($0.09 per share)								(21,237)
Dividends accrued on unvested restricted stock units								8
Deferred compensation adjustments, net of tax								(145)
ADTRAN RSUs and restricted stock vested							(1,026)	(1,115)
ADTRAN Stock options exercised							824	164
Redemption of redeemable non-controlling interest							2,986	371
Foreign currency remeasurement of redeemable non-controlling interest								(9,604)
Ending Balance	(691,996)						(691,996)	(243,908)	55,338
As Reported [Member] | Accumulated Other Comprehensive Income [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				47,461	47,461	47,461	47,461	26,126
Other comprehensive income (loss), net of tax							(36,568)	21,335
Ending Balance	10,893						10,893	47,461	26,126
As Reported [Member] | Additional Paid-In Capital [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				795,304	795,304	795,304	795,304	895,834
Remeasurement of redeemable non-controlling interest							(1,175)
Deferred compensation adjustments, net of tax							(368)
Modification of stock options							(190)
ADTRAN Stock-based compensation expense							14,825	16,016
Ending Balance	808,913						808,913	795,304	$ 895,834
As Reported [Member] | Additional Paid-In Capital [Member] | Adtran Networks SE [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Reclassification and remeasurement from equity to mezzanine equity for non-controlling interests in Adtran Networks								(116,895)
ADTRAN Stock options exercised								323
ADTRAN Stock-based compensation expense							517	26
Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				11,435	11,435	11,435	11,435
Other comprehensive income (loss), net of tax	573	$ (186)	$ (67)	(28)	(95)	(281)	292	69
Ending Balance	(7,463)						(7,463)	11,435
Adjustment [Member] | Retained Deficit [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				12,202	12,202	12,202	12,202
Net loss							(9,019)	(2,563)
Annual recurring compensation earned								1,399
Acquisition of Adtran Networks								3,762
Foreign currency remeasurement of redeemable non-controlling interest								9,604
Ending Balance	3,183						3,183	12,202
Adjustment [Member] | Accumulated Other Comprehensive Income [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				69	69	69	69
Other comprehensive income (loss), net of tax							292	69
Ending Balance	$ 361						361	69
Adjustment [Member] | Additional Paid-In Capital [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning Balance				$ (836)	$ (836)	$ (836)	(836)
Mezzanine equity for non-controlling interest in adtran networks for adtran networks stock options exercised								(1,175)
Modification of stock options								339
Ending Balance								$ (836)
Adjustment [Member] | Additional Paid-In Capital [Member] | Adtran Networks SE [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
ADTRAN Stock-based compensation expense							$ 836