Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Total Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jul. 04, 2021	Apr. 04, 2021	Jun. 28, 2020	Mar. 29, 2020	Jul. 04, 2021	Jun. 28, 2020
Equity [Abstract]
Net income (loss)	$ 43,972	$ 28,741	$ (67,881)	$ (11,219)	$ 72,713	$ (79,100)
Foreign currency translation adjustments, net of tax	(22,257)		(44,671)		30,507	(22,881)
Adjustments to pension and postretirement liability, net of tax	763		372		1,527	755
Total comprehensive income (loss)	22,478		(112,180)		104,747	(101,226)
Less: Comprehensive income (loss) attributable to noncontrolling interests	(21)		171		(143)	(9)
Comprehensive income (loss) attributable to Belden	$ 22,499		$ (112,351)		$ 104,890	$ (101,217)