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
	Jun. 28, 2020	Mar. 29, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 28, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 953,035	$ 965,819	$ 1,431,329	$ 1,387,588	$ 965,819
Net current period other comprehensive gain (loss) attributable to Belden	(44,299)	22,173	(16,653)	29,010
Ending balance	829,882	953,035	$ 1,433,533	$ 1,431,329	829,882
Foreign  Currency Translation Component
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(18,225)			(18,225)
Other comprehensive loss attributable to Belden before reclassifications					(22,878)
Amounts reclassified from accumulated other comprehensive income (loss)					0
Net current period other comprehensive gain (loss) attributable to Belden					(22,878)
Ending balance	(41,103)				(41,103)
Pension and  Other  Postretirement Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		(45,193)			(45,193)
Other comprehensive loss attributable to Belden before reclassifications					0
Amounts reclassified from accumulated other comprehensive income (loss)					755
Net current period other comprehensive gain (loss) attributable to Belden					755
Ending balance	(44,438)				(44,438)
Accumulated Other  Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		$ (63,418)			(63,418)
Other comprehensive loss attributable to Belden before reclassifications					(22,878)
Amounts reclassified from accumulated other comprehensive income (loss)					755
Net current period other comprehensive gain (loss) attributable to Belden					(22,123)
Ending balance	$ (85,541)				$ (85,541)