Income Taxes Taxes by Jurisdiction (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Income Taxes [Line Items]
Federal and state income taxes	$ (2,251)	$ (3,420)	$ 1,284	$ 6,678
Foreign income taxes	77	103	475	383
Income tax expense (benefit)	$ (2,174)	$ (3,317)	$ 1,759	$ 7,061
Effective income tax rate	19.50%	35.90%	35.10%	38.50%