Income (loss) per Share - Basis for Income Per Share Computations (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Numerator:
Income from continuing operations	$ 20,569	$ 38,031	$ 38,633	$ 107,361
Net Income (Loss) Attributable to Noncontrolling Interest	(85)	6	(79)	(60)
Preferred Stock Dividends, Income Statement Impact	0	(971)	0	(18,437)
Income from continuing operations attributable to Belden common stockholders	20,484	37,066	38,554	88,864
Add: Loss from discontinued operations, net of tax	(6,231)	(335,046)	(103,395)	(336,908)
Add: Gain on disposal of discontinued operations, net of tax	2,743	0	2,743	0
Net income (loss) attributable to Belden common stockholders	$ 16,996	$ (297,980)	$ (62,098)	$ (248,044)
Denominator:
Weighted average shares outstanding, basic (in shares)	44,567	44,444	44,834	41,090
Effect of dilutive common stock equivalents (in shares)	142	166	134	209
Weighted average shares outstanding, diluted (in shares)	44,709	44,610	44,968	41,299