Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenues	$ 1,862,716	$ 2,131,278	$ 2,165,702
Cost of sales	(1,199,427)	(1,337,773)	(1,335,791)
Gross profit	663,289	793,505	829,911
Selling, general and administrative expenses	(366,188)	(417,329)	(411,352)
Research and development expenses	(107,296)	(94,360)	(91,552)
Amortization of intangibles	(64,395)	(74,609)	(75,140)
Gain from patent litigation	0	0	62,141
Operating income	125,410	207,207	314,008
Interest expense, net	(58,888)	(55,814)	(60,839)
Non-operating pension benefit (cost)	(395)	1,017	(99)
Loss on debt extinguishment	0	0	(22,990)
Income from continuing operations before taxes	66,127	152,410	230,080
Income tax expense	(11,724)	(42,519)	(62,936)
Income from continuing operations	54,403	109,891	167,144
Loss from discontinued operations, net of tax	(99,513)	(486,667)	(6,433)
Gain on disposal	(9,948)	0	0
Net income (loss)	(55,058)	(376,776)	160,711
Less: Net income (loss) attributable to noncontrolling interest	104	239	(183)
Net income (loss) attributable to Belden	(55,162)	(377,015)	160,894
Less: Preferred stock dividends	0	18,437	34,931
Net income (loss) attributable to Belden common stockholders	$ (55,162)	$ (395,452)	$ 125,963
Weighted average number of common shares and equivalents:
Basic (in shares)	44,778	42,203	40,675
Diluted (in shares)	44,937	42,416	40,956
Basic income (loss) per share attributable to Belden common stockholders:
Continuing operations attributable to Belden common stockholders (in dollars per share)	$ 1.21	$ 2.16	$ 3.25
Discontinued operations attributable to Belden common stockholders (in dollars per share)	(2.22)	(11.53)	(0.16)
Disposal of discontinued operations attributable to Belden common stockholders (in dollars per share)	(0.22)	0	0
Net income (loss) attributable to Belden common stockholders (in dollars per share)	(1.23)	(9.37)	3.10
Diluted income (loss) per share attributable to Belden common stockholders:
Continuing operations attributable to Belden common stockholders (in dollars per share)	1.21	2.15	3.23
Discontinued operations attributable to Belden common stockholders (in dollars per share)	(2.22)	(11.53)	(0.16)
Disposal of discontinued operations attributable to Belden common stockholders (in dollars per share)	(0.22)	0	0
Diluted income (loss) per share attributable to Belden stockholders:	$ (1.23)	$ (9.37)	$ 3.08