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