Loss per Share - Summary of Calculations of Basic and Diluted Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Numerator
Net Loss attributable to ADTRAN Holdings, Inc.	$ (46,111)	$ (33,348)	$ (49,667)	$ (330,765)	$ (380,432)	$ (413,780)	$ (459,891)		$ (268,852)	$ (2,037)
Effect of redemption of RNCI							2,981
Net loss attributable to ADTRAN Holdings, Inc. common stockholders							$ (456,910)		$ (268,852)	$ (2,037)
Denominator
Weighted average number of shares – basic	79,091	78,952	78,852	78,814	78,803	78,873	78,928		78,416	62,346
Effect of dilutive securities:
Weighted average number of shares – diluted	79,091	78,952	78,852	78,814	78,803	78,873	78,928		78,416	62,346
Loss per share attributable to ADTRAN Holdings, Inc. - basic	$ (0.58)	$ (0.38)	$ (0.63)	$ (4.2)	$ (4.83)	$ (5.21)	$ (5.79)	[1]	$ (3.43)	$ (0.03)
Loss per share attributable to ADTRAN Holdings, Inc. - diluted	$ (0.58)	$ (0.38)	$ (0.63)	$ (4.2)	$ (4.83)	$ (5.21)	$ (5.79)	[1]	$ (3.43)	$ (0.03)

[1] Loss per common share attributable to ADTRAN Holdings, Inc. - basic and diluted - reflects a $3.0 million effect of redemption of RNCI for the year ended December 31, 2024. See Note 19 for additional information.