Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Income Statement [Abstract]
Revenues	$ 475,839	$ 533,098	$ 1,364,176	$ 1,581,590
Cost of sales	(308,247)	(334,293)	(876,143)	(990,857)
Gross profit	167,592	198,805	488,033	590,733
Selling, general and administrative expenses	(85,037)	(98,245)	(275,129)	(298,654)
Research and development expenses	(30,324)	(23,992)	(81,633)	(72,014)
Amortization of intangibles	(16,104)	(19,026)	(48,306)	(56,258)
Operating income	36,127	57,542	82,965	163,807
Interest expense, net	(15,607)	(14,002)	(43,188)	(41,951)
Non-operating pension benefit	680	544	2,079	1,684
Income from continuing operations before taxes	21,200	44,084	41,856	123,540
Income tax expense	(631)	(6,053)	(3,223)	(16,179)
Income from continuing operations	20,569	38,031	38,633	107,361
Loss from discontinued operations, net of tax	(6,231)	(335,046)	(103,395)	(336,908)
Gain on disposal of discontinued operations, net of tax	2,743	0	2,743	0
Net income (loss)	17,081	(297,015)	(62,019)	(229,547)
Less: Net income (loss) attributable to noncontrolling interest	85	(6)	79	60
Net income (loss) attributable to Belden	16,996	(297,009)	(62,098)	(229,607)
Less: Preferred stock dividends	0	971	0	18,437
Net income (loss) attributable to Belden common stockholders	$ 16,996	$ (297,980)	$ (62,098)	$ (248,044)
Weighted average number of common shares and equivalents:
Basic (in shares)	44,567	44,444	44,834	41,090
Diluted (in shares)	44,709	44,610	44,968	41,299
Basic income (loss) per share attributable to Belden common stockholders:
Continuing operations attributable to Belden common stockholders (in dollars per share)	$ 0.46	$ 0.83	$ 0.86	$ 2.16
Discontinued operations attributable to Belden common stockholders (in dollars per share)	(0.14)	(7.54)	(2.31)	(8.20)
Disposal of discontinued operations attributable to Belden common stockholders (in dollars per share)	0.06	0	0.06	0
Net income (loss) per share attributable to Belden common stockholders (in dollars per share)	0.38	(6.70)	(1.39)	(6.04)
Diluted income (loss) per share attributable to Belden common stockholders:
Continuing operation attributable to Belden common stockholders (in dollars per share)	0.46	0.83	0.86	2.15
Discontinued operations attributable to Belden common stockholders (in dollars per share)	(0.14)	(7.54)	(2.31)	(8.20)
Disposal of discontinued operations attributable to Belden common stockholders (in dollars per share)	0.06	0	0.06	0
Net income (loss) per share attributable to Belden common stockholders (in dollars per share)	$ 0.38	$ (6.70)	$ (1.39)	$ (6.04)
Comprehensive loss attributable to Belden	$ (34,921)	$ (263,530)	$ (136,138)	$ (183,811)
Common stock dividends declared per share (in dollars per share)	$ 0.05	$ 0.05	$ 0.15	$ 0.15