Income Taxes (Income Tax Reconciliation, Narrative) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 26, 2020	Sep. 28, 2019	Dec. 28, 2019
Income Tax Disclosure [Abstract]
Effective income tax (benefit) rate	(0.00%)	0.20%
Deferred Tax Liabilities, Net	$ 91		$ 91

Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=120406818&loc=d3e31931-109318

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant