Acquisitions - Schedule of Pro Forma Information (Details) - Opterna International Corp. - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 29, 2019	Sep. 29, 2019
Business Acquisition [Line Items]
Revenues	$ 533,098	$ 1,590,206
Net income from continuing operations attributable to Belden common stockholders	$ 39,721	$ 91,459
Diluted income from continuing operations per share attributable to Belden common stockholders	$ 0.89	$ 2.21

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