Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014
Income Taxes
Income tax expense	$ 956	$ 5,937	$ 1,645	$ 7,407
Effective income tax rate (as a percent)	11.20%	29.40%	10.50%	24.90%
Gross unrecognized tax benefits	$ 3,900		$ 3,900
Amount of estimated decrease in unrecognized tax benefits	$ 600		$ 600