Segment Information Segment Income or Loss Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2020	Sep. 27, 2019	Sep. 25, 2020	Sep. 27, 2019
Segment Reporting Information [Line Items]
Operating income (loss)	$ (1,621)	$ 22,549	$ (29,224)	$ 6,377
Unallocated Corporate Expenses	(50,545)	(52,991)	(152,659)	(154,940)
Stock-based compensation	(3,930)	(4,096)	(13,737)	(8,719)
Amortization of intangibles	(752)	(2,080)	(3,214)	(6,242)
Nonoperating Income (Expense)	(2,974)	(10,289)	(10,419)	(16,890)
Income (loss) before income taxes	(4,595)	12,260	(39,643)	(10,513)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	4,177	29,915	(10,470)	23,254
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Unallocated Corporate Expenses	$ (1,116)	$ (1,190)	$ (1,803)	$ (1,916)