Stockholders' Equity - Share repurchase programs (Details) - USD ($) $ in Thousands, shares in Millions	6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jan. 31, 2017	Aug. 31, 2015
Stockholders' Equity
Number of shares of common stock issued	0.6
Program Amount authorized to repurchase			$ 100,000	$ 100,000
Repurchase of common stock (in shares)	0.0	0.8
Repurchase of common stock		$ 38,100