Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (778)	$ 1,416	$ 23,683	$ 14,385
Other comprehensive income – unrealized gain on available-for-sale marketable debt securities, net of income tax	0	0	0	14
Comprehensive (loss) income	$ (778)	$ 1,416	$ 23,683	$ 14,399