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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. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Sep. 29, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 1,433,533	$ 1,431,329	$ 1,387,588	$ 1,351,110	$ 1,292,146	$ 1,434,866	$ 1,387,588
Net current period other comprehensive gain attributable to Belden	33,853	(16,653)	29,010	(17,267)	61,011	(31,392)
Ending balance	1,144,810	$ 1,433,533	1,431,329	$ 1,390,302	$ 1,351,110	$ 1,292,146	1,144,810
Foreign Currency Translation Component
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(41,882)				(41,882)
Other comprehensive income attributable to Belden before reclassifications							45,205
Amounts reclassified from accumulated other comprehensive income							0
Net current period other comprehensive gain attributable to Belden							45,205
Ending balance	3,323						3,323
Pension and Other Postretirement Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(33,025)				(33,025)
Other comprehensive income attributable to Belden before reclassifications							0
Amounts reclassified from accumulated other comprehensive income							591
Net current period other comprehensive gain attributable to Belden							591
Ending balance	(32,434)						(32,434)
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			$ (74,907)				(74,907)
Other comprehensive income attributable to Belden before reclassifications							45,205
Amounts reclassified from accumulated other comprehensive income							591
Net current period other comprehensive gain attributable to Belden							45,796
Ending balance	$ (29,111)						$ (29,111)