Acquisitions - Schedule of Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Opterna International Corp.
Business Acquisition [Line Items]
Revenues	$ 620,318	$ 666,048	$ 1,853,639	$ 1,957,512
Net income attributable to Belden common stockholders	$ (295,312)	$ 77,417	$ (242,579)	$ 87,250
Diluted income (loss) per share attributable to Belden common stockholders (in usd per share)	$ (6.64)	$ 1.62	$ (5.90)	$ 2.11
Snell Advanced Media
Business Acquisition [Line Items]
Revenues		$ 659,003		$ 1,944,628
Net income attributable to Belden common stockholders		$ 92,769		$ 126,937
Diluted income (loss) per share attributable to Belden common stockholders (in usd per share)		$ 2.13		$ 3.08