Income Per Share - Basis for Income Per Share Computations (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Income from continuing operations	$ 54,403	$ 109,891	$ 167,144
Less: Net income (loss) attributable to noncontrolling interest	104	239	(183)
Less: Preferred stock dividends	0	18,437	34,931
Income from continuing operations attributable to Belden common stockholders	54,299	91,215	132,396
Loss from discontinued operations, net of tax	(99,513)	(486,667)	(6,433)
Gain on disposal	(9,948)	0	0
Net income (loss) attributable to Belden common stockholders	$ (55,162)	$ (395,452)	$ 125,963
Denominator:
Weighted average shares outstanding, basic (in shares)	44,778	42,203	40,675
Effect of dilutive common stock equivalents (in shares)	159	213	281
Weighted average shares outstanding, diluted (in shares)	44,937	42,416	40,956