Disposals - Operating Results of the Disposal Group (Details) - Grass Valley - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Asset impairment of discontinued operations	$ (113,000)	$ (521,400)
Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	109,195	360,496
Cost of sales	(70,199)	(208,173)
Gross profit	38,996	152,323
Selling, general and administrative expenses	(39,947)	(93,796)
Research and development expenses	(15,083)	(37,172)
Amortization of intangibles	0	(12,782)
Asset impairment of discontinued operations	(113,007)	(521,441)
Interest expense, net	(432)	(819)
Non-operating pension cost	(169)	(221)
Loss before taxes	$ (129,642)	$ (513,908)