Acquisitions - Schedule of Pro Forma Information (Details) - OTN Systems N.V. - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2021	Jun. 28, 2020	Jul. 04, 2021	Jun. 28, 2020
Business Acquisition [Line Items]
Revenues	$ 603,171	$ 432,941	$ 1,140,750	$ 901,641
Net income from continuing operations attributable to Belden common stockholders	$ 38,133	$ 2,015	$ 61,503	$ 13,213
Diluted income from continuing operations per share attributable to Belden common stockholders	$ 0.84	$ 0.05	$ 1.36	$ 0.29