Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Components of Other Comprehensive Income (Loss), Net of Tax (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
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 845,460	$ 757,051	$ 953,035	$ 965,819	$ 757,051
Net current period other comprehensive income attributable to Belden	(21,494)	53,528	(44,299)	22,173
Ending balance	874,098	845,460	829,882	953,035	874,098
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(138,126)	(191,851)	(41,095)	(63,418)	(191,851)
Other comprehensive income attributable to Belden before reclassifications					31,910
Amounts reclassified from accumulated other comprehensive income (loss)					550
Net current period other comprehensive income attributable to Belden	(21,265)	53,725	(44,446)	22,323	32,460
Ending balance	(159,391)	(138,126)	$ (85,541)	$ (41,095)	(159,391)
Foreign Currency Translation Component
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(131,181)			(131,181)
Other comprehensive income attributable to Belden before reclassifications					31,910
Amounts reclassified from accumulated other comprehensive income (loss)					(977)
Net current period other comprehensive income attributable to Belden					30,933
Ending balance	(100,248)				(100,248)
Pension and Other  Postretirement Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		$ (60,670)			(60,670)
Other comprehensive income attributable to Belden before reclassifications					0
Amounts reclassified from accumulated other comprehensive income (loss)					1,527
Net current period other comprehensive income attributable to Belden					1,527
Ending balance	$ (59,143)				$ (59,143)