Consolidated Statement of Shareholders' Equity - 9 months ended Sep. 29, 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	42,549			42,549
Exercise of common stock options (in shares)		157,000
Exercise of common stock options	2,084	$ 1	2,083	0
Stock-based compensation (in shares)		261,000
Stock-based compensation	10,098	$ 3	10,095	0
Repurchases of common stock (in shares)		(6,015,000)
Repurchases of common stock	$ (198,239)	$ (60)	(12,178)	(186,001)
Balance (in shares) at Sep. 29, 2018	33,216,000	33,216,000
Balance at Sep. 29, 2018	$ (54,352)	$ 332	$ 0	$ (54,684)