Quarterly Sales and Earnings Data - Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 01, 2016	Oct. 02, 2015	Jul. 03, 2015	Apr. 03, 2015	Jan. 02, 2015	Oct. 03, 2014	Jul. 04, 2014	Apr. 04, 2014	Jan. 01, 2016	Jan. 02, 2015	Jan. 03, 2014
Business Acquisition [Line Items]
Sales	$ 317,567	$ 146,637	$ 174,890	$ 161,320	$ 169,726	$ 171,699	$ 172,081	$ 174,281	$ 800,414	$ 687,787	$ 663,945
Gross profit	73,140	51,646	57,951	52,398	57,214	58,118	58,470	57,596	235,135	231,398	219,313
Net income (loss)	$ (24,907)	$ 22	$ 9,283	$ 8,008	$ 14,176	$ 14,012	$ 12,348	$ 14,922	$ (7,594)	$ 55,458	$ 36,267
Earnings Per Share, Basic (in dollars per share)	$ (0.85)	$ 0.00	$ 0.36	$ 0.32	$ 0.57	$ 0.56	$ 0.50	$ 0.61	$ (0.29)	$ 2.23	$ 1.51
Earnings Per Share, Diluted (in dollars per share)	$ (0.85)	$ 0.00	$ 0.35	$ 0.31	$ 0.54	$ 0.54	$ 0.48	$ 0.58	$ (0.29)	$ 2.14	$ 1.43
Lake Region Medical [Member]
Business Acquisition [Line Items]
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	$ 138,600								$ 138,600
Spinoff [Member] | Lake Region Medical [Member]
Business Acquisition [Line Items]
Transaction costs	$ 57,100	$ 13,000