Stockholders' Equity Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Mar. 31, 2019	Jul. 01, 2018	Apr. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Accumulated Other Comprehensive Loss, Net of Tax
Balance, beginning of year		$ (61,673)		$ (46,198)	$ (61,673)	$ (46,198)
Current-period other comprehensive income (loss)	$ 3,835	6,025	$ (4,325)	(5,927)	9,860	(10,252)
Balance, end of the period	(51,813)		(56,450)		(51,813)	(56,450)
Foreign Currency Translation
Accumulated Other Comprehensive Loss, Net of Tax
Balance, beginning of year		(61,673)		(45,149)	(61,673)	(45,149)
Current-period other comprehensive income (loss)					9,860	(10,369)
Balance, end of the period	(51,813)		(55,518)		(51,813)	(55,518)
Pension
Accumulated Other Comprehensive Loss, Net of Tax
Balance, beginning of year		$ 0		$ (1,049)	0	(1,049)
Current-period other comprehensive income (loss)					0	117
Balance, end of the period	$ 0		$ (932)		$ 0	$ (932)

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e637-108580

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=114867106&loc=SL7669686-108580

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=114867106&loc=d3e681-108580

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant