Segment Information Segment Income or Loss Reconciliation (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 02, 2021	Jun. 26, 2020	Jul. 02, 2021	Jun. 26, 2020
Segment Reporting Information [Line Items]
Operating income (loss)		$ 2,136	$ (9,554)	$ (1,708)	$ (27,603)
Unallocated Corporate Expenses		(58,369)	(47,327)	(117,358)	(102,114)
Stock-based compensation		(4,033)	(3,548)	(12,431)	(9,807)
Amortization of intangibles		0	(807)	(507)	(2,462)
Nonoperating expense, net		(2,777)	(4,269)	(4,361)	(7,445)
Loss before income taxes		(641)	(13,823)	(6,069)	(35,048)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income (loss)		6,551	(5,115)	11,619	(14,647)
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Unallocated Corporate Expenses	[1]	$ (382)	$ (84)	$ (389)	$ (687)

[1] Together with amortization of intangibles and stock-based compensation, the Company does not allocate restructuring and related charges to the operating income (loss) for each segment because management does not include this information in the measurement of the performance of the operating segments.