Consolidated Statement of Shareholders' Equity - 6 months ended Jun. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]
Balance (in shares) at Dec. 30, 2017	38,813,000	38,813,000
Balance at Dec. 30, 2017	$ 89,156	$ 388	$ 0	$ 88,768
Net income	24,292			24,292
Exercise of common stock options (in shares)		124,000
Exercise of common stock options	1,596	$ 1	1,595	0
Stock-based compensation (in shares)		254,000
Stock-based compensation	6,742	$ 3	6,739	0
Repurchases of common stock (in shares)		(4,298,000)
Repurchases of common stock	$ (142,940)	$ (43)	(8,334)	(134,563)
Balance (in shares) at Jun. 30, 2018	34,893,000	34,893,000
Balance at Jun. 30, 2018	$ (21,154)	$ 349	$ 0	$ (21,503)