Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Components of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 965,819	$ 1,387,588
Net current period other comprehensive gain attributable to Belden	22,173	29,010
Ending balance	953,035	$ 1,431,329
Foreign  Currency Translation Component
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(18,225)
Other comprehensive income attributable to Belden before reclassifications	21,940
Amounts reclassified from accumulated other comprehensive income	0
Net current period other comprehensive gain attributable to Belden	21,940
Ending balance	3,715
Pension and  Other  Postretirement Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(45,193)
Other comprehensive income attributable to Belden before reclassifications	0
Amounts reclassified from accumulated other comprehensive income	383
Net current period other comprehensive gain attributable to Belden	383
Ending balance	(44,810)
Accumulated Other  Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(63,418)
Other comprehensive income attributable to Belden before reclassifications	21,940
Amounts reclassified from accumulated other comprehensive income	383
Net current period other comprehensive gain attributable to Belden	22,323
Ending balance	$ (41,095)