Income (loss) per Share - Basis for Income Per Share Computations (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2021	Jun. 28, 2020	Jul. 04, 2021	Jun. 28, 2020
Numerator:
Income from continuing operations	$ 43,972	$ 3,173	$ 72,713	$ 18,064
Less: Net income (loss) attributable to noncontrolling interest	208	24	283	(6)
Income from continuing operations attributable to Belden stockholders	43,764	3,149	72,430	18,070
Add: Loss from discontinued operations, net of tax	0	(71,054)	0	(97,164)
Net income (loss) attributable to Belden stockholders	$ 43,764	$ (67,905)	$ 72,430	$ (79,094)
Denominator:
Weighted average shares outstanding, basic (in shares)	44,759	44,557	44,717	44,969
Effect of dilutive common stock equivalents (in shares)	503	108	445	128
Weighted average shares outstanding, diluted (in shares)	45,262	44,665	45,162	45,097