Acquisitions - Schedule of Pro Forma Information (Details) - OTN Systems N.V. - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2021	Sep. 27, 2020	Oct. 03, 2021	Sep. 27, 2020
Business Acquisition [Line Items]
Revenues	$ 631,338	$ 479,137	$ 1,770,941	$ 1,380,778
Net income from continuing operations attributable to Belden common stockholders	$ 42,041	$ 17,071	$ 114,752	$ 30,285
Diluted income from continuing operations per share attributable to Belden common stockholders	$ 0.93	$ 0.38	$ 2.54	$ 0.67