Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Total Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Sep. 29, 2019	Sep. 30, 2018
Equity [Abstract]
Net income (loss)	$ (297,015)	$ 42,290	$ 25,178	$ 85,858	$ 28,792	$ 2,570	$ (229,547)	$ 117,220
Foreign currency translation gain (loss), net of $0.2 million, $0.5 million, $0.6 million, and $0.7 million tax, respectively	33,732			(17,904)			45,619	10,943
Adjustments to pension and postretirement liability, net of $0.0 million, $0.4 million, $0.2 million, and $0.9 million tax, respectively	120			637			591	1,409
Total comprehensive income (loss)	(263,163)			68,591			(183,337)	129,572
Less: Comprehensive income (loss) attributable to noncontrolling interests	367			(29)			474	(155)
Comprehensive income (loss) attributable to Belden	(263,530)			68,620			(183,811)	129,727
Foreign currency translation, tax income (loss)	200			500			600	700
Adjustments to pension and postretirement liability, tax	$ 0			$ 400			$ 200	$ 900