Income Taxes (Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Jan. 01, 2019	Jan. 02, 2018
Income Tax Disclosure [Abstract]
Federal income tax provision (benefit) at federal rate	$ 368	$ (1,825)	$ (12,814)
State income tax provision (benefit), net of federal tax	168	(623)	(1,790)
Other permanent differences	327	70	674
Foreign rate differential	0	0	(463)
Tax credits	(408)	(602)	(808)
Change in valuation allowance	(913)	2,600	(159)
Tax rate change	23	(248)	13,632
Deferred tax asset write-off	566	212	2,618
Other items, net	(27)	168	(1,097)
Total provision (benefit) for income taxes	$ 104	$ (248)	$ (207)
Effective income tax rate	5.90%	2.90%	0.50%