Summary of Significant Accounting Policies - Net income per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 01, 2019	Oct. 02, 2018	Jul. 03, 2018	Apr. 03, 2018	Jan. 02, 2018	Oct. 03, 2017	Jul. 04, 2017	Apr. 04, 2017	Jan. 01, 2019	Jan. 02, 2018	Jan. 03, 2017
Advertising Costs
Advertising costs									$ 6,100	$ 6,100	$ 7,400
Net income per share, basic and diluted
Net income	$ 16,178	$ 28,475	$ 28,353	$ 26,029	$ 57,738	$ 26,445	$ 38,166	$ 35,043	$ 99,035	$ 157,392	$ 139,494
Basic weighted average shares outstanding (in shares)									45,263	46,930	47,981
Dilutive effect of equity awards (in shares)									952	1,222	1,391
Diluted weighted average shares outstanding (in shares)									46,215	48,152	49,372
Basic net income per share (in dollars per share)	$ 0.36	$ 0.63	$ 0.62	$ 0.57	$ 1.26	$ 0.57	$ 0.80	$ 0.74	$ 2.19	$ 3.35	$ 2.91
Diluted net income per share (in dollars per share)	$ 0.35	$ 0.61	$ 0.61	$ 0.56	$ 1.24	$ 0.56	$ 0.78	$ 0.71	$ 2.14	$ 3.27	$ 2.83
Antidilutive securities excluded from calculation of basic earnings per share (in shares)									1,500	1,600	1,400
Restricted Shares and Restricted Share Units
Net income per share, basic and diluted
Antidilutive securities excluded from calculation of basic earnings per share (in shares)									1,700	1,700	1,900