Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Total Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Equity [Abstract]
Net income (loss)	$ 28,741	$ (11,219)
Foreign currency translation adjustments, net of $0.0 million and $1.0 million tax, respectively	52,764	21,790
Adjustments to pension and postretirement liability, net of $0.2 million and $0.1 million tax, respectively	764	383
Total comprehensive income	82,269	10,954
Less: Comprehensive loss attributable to noncontrolling interests	(122)	(180)
Comprehensive income attributable to Belden	82,391	11,134
Foreign currency translation, tax income (loss)	(0)	(1,000)
Adjustments to pension and postretirement liability, Tax	$ 100	$ 200