Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 25,603	$ 25,745	$ 49,286	$ 40,130
Other comprehensive income – unrealized gain on available-for-sale marketable debt securities, net of income tax	0	0	0	14
Comprehensive income	$ 25,603	$ 25,745	$ 49,286	$ 40,144