Acquisitions - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 29, 2019	Apr. 15, 2019	Dec. 31, 2018	Feb. 08, 2018
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Goodwill	$ 1,265,006		$ 1,557,653
Opterna International Corp.
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Receivables		$ 5,308
Inventory		7,470
Prepaid and other current assets		566
Property, plant, and equipment		1,328
Intangible assets		28,000
Goodwill		35,565
Deferred income taxes		36
Operating lease right-to-use assets		2,204
Other long-lived assets		2,070
Total assets acquired		82,547
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Accounts payable		4,847
Accrued liabilities		4,346
Long-term deferred tax liability		7,342
Long-term operating lease liability		1,923
Other long-term liabilities		7,153
Total liabilities assumed		25,611
Net assets		56,936
Noncontrolling interests		5,195
Net assets attributable to Belden		$ 51,741
Snell Advanced Media
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Receivables				$ 16,551
Inventory				15,084
Prepaid and other current assets				3,799
Property, plant, and equipment				7,716
Intangible assets				51,000
Goodwill				103,466
Deferred income taxes				1,388
Other long-lived assets				3,046
Total assets acquired				202,050
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Accounts payable				11,825
Accrued liabilities				25,135
Deferred revenue				8,860
Long-term debt				19,315
Postretirement benefits				31,774
Other long-term liabilities				591
Total liabilities assumed				97,500
Net assets				$ 104,550