Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Total Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Oct. 03, 2021	Jul. 04, 2021	Apr. 04, 2021	Sep. 27, 2020	Jun. 28, 2020	Mar. 29, 2020	Oct. 03, 2021	Sep. 27, 2020
Equity [Abstract]
Net income (loss)	$ 41,317	$ 43,972	$ 28,741	$ 17,081	$ (67,881)	$ (11,219)	$ 114,030	$ (62,019)
Foreign currency translation adjustments, net of tax	27,221			(52,910)			57,728	(75,791)
Adjustments to pension and postretirement liability, net of tax	758			1,136			2,285	1,891
Total comprehensive income (loss)	69,296			(34,693)			174,043	(135,919)
Less: Comprehensive income (loss) attributable to noncontrolling interests	(94)			228			(237)	219
Comprehensive income (loss) attributable to Belden	$ 69,390			$ (34,921)			$ 174,280	$ (136,138)