Comprehensive Income and Accumulated Other Comprehensive Income (Loss) - Components of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 27, 2020	Jun. 28, 2020	Mar. 29, 2020	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 27, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 829,882	$ 953,035	$ 965,819	$ 1,433,533	$ 1,431,329	$ 1,387,588	$ 965,819
Other comprehensive loss attributable to Belden before reclassifications							(86,076)
Amounts reclassified from accumulated other comprehensive income (loss)							12,036
Net current period other comprehensive gain (loss) attributable to Belden	(51,774)	(44,299)	22,173	33,853	(16,653)	29,010
Ending balance	798,587	$ 829,882	953,035	$ 1,144,810	$ 1,433,533	$ 1,431,329	798,587
Accumulated Other  Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(63,418)				(63,418)
Net current period other comprehensive gain (loss) attributable to Belden							(74,040)
Ending balance	(137,458)						(137,458)
Accumulated Foreign Currency Adjustment Attributable to Noncontrolling Interest
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							(86,076)
Amounts reclassified from accumulated other comprehensive income (loss)							10,145
Net current period other comprehensive gain (loss) attributable to Belden							(75,931)
Ending balance	(94,156)						(94,156)
Accumulated Defined Benefit Plans Adjustment Attributable to Noncontrolling Interest
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)							1,891
Net current period other comprehensive gain (loss) attributable to Belden							1,891
Ending balance	$ (43,302)						$ (43,302)