Income Taxes Effective Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory federal income tax provision (benefit)	$ 2,717	$ 6,085	$ 1
State income taxes (benefit), net of federal provision (benefit)	572	403	6
Change in valuation allowance	0	(30,374)	2,959
Employment tax credits	(1,947)	(5,408)	(2,710)
Non-deductible expenses	336	965	0
Federal rate change	(762)	0	0
Miscellaneous	(312)	244	(256)
Provision (benefit) for income taxes	$ 604	$ (28,085)	$ 0

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to state and local income tax expense (benefit).

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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