Income (loss) per Share - Basis for Income Per Share Computations (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2021	Sep. 27, 2020	Oct. 03, 2021	Sep. 27, 2020
Numerator:
Income from continuing operations	$ 41,317	$ 20,569	$ 114,030	$ 38,633
Less: Net income attributable to noncontrolling interest	53	85	336	79
Income from continuing operations attributable to Belden stockholders	41,264	20,484	113,694	38,554
Add: Loss from discontinued operations, net of tax	0	(6,231)	0	(103,395)
Gain on disposal of discontinued operations, net of tax	0	2,743	0	2,743
Net income (loss) attributable to Belden stockholders	$ 41,264	$ 16,996	$ 113,694	$ (62,098)
Denominator:
Weighted average shares outstanding, basic (in shares)	44,851	44,567	44,762	44,834
Effect of dilutive common stock equivalents (in shares)	574	142	480	134
Weighted average shares outstanding, diluted (in shares)	45,425	44,709	45,242	44,968