Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Components of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 757,051	$ 965,819
Other comprehensive loss attributable to Belden before reclassifications	52,961
Amounts reclassified from accumulated other comprehensive income (loss)	764
Net current period other comprehensive gain (loss) attributable to Belden	53,528	22,173
Ending balance	845,460	953,035
Accumulated Other  Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(191,851)
Ending balance	(138,126)
Foreign Currency Translation Component
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(131,181)
Other comprehensive loss attributable to Belden before reclassifications	52,961
Amounts reclassified from accumulated other comprehensive income (loss)	0
Net current period other comprehensive gain (loss) attributable to Belden	52,961
Ending balance	(78,220)
Pension and Other  Postretirement Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(60,670)
Other comprehensive loss attributable to Belden before reclassifications	0
Amounts reclassified from accumulated other comprehensive income (loss)	764
Net current period other comprehensive gain (loss) attributable to Belden	764
Ending balance	(59,906)
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(191,851)	(63,418)
Net current period other comprehensive gain (loss) attributable to Belden	53,725	22,323
Ending balance	$ (138,126)	$ (41,095)