Segment Information Segment Income or Loss Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Segment Reporting Information [Line Items]
Operating income (loss)	$ 22,549	$ (3,651)	$ 6,377	$ (12,336)
Unallocated Corporate Expenses	(52,991)	(53,753)	(154,940)	(161,224)
Stock-based compensation	(4,096)	(5,433)	(8,719)	(14,202)
Amortization of intangibles	(2,080)	(2,087)	(6,242)	(6,281)
Nonoperating Income (Expense)	(10,289)	(3,237)	(16,890)	(9,190)
Income (loss) before income taxes	12,260	(6,888)	(10,513)	(21,526)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	29,915	4,863	23,254	11,729
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Unallocated Corporate Expenses	$ (1,190)	$ (994)	$ (1,916)	$ (3,582)

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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