Net Income per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Net Income per Common Share [Abstract]
Net income	$ 3,744	$ (778)	$ 24,292	$ 23,683
Basic weighted-average shares outstanding	36,138,000	41,716,000	37,191,000	42,233,000
Dilutive effect of stock-based awards	706,000	0	905,000	847,000
Diluted weighted-average shares outstanding	36,844,000	41,716,000	38,096,000	43,080,000
Net income per share – basic (in USD per share)	$ 0.10	$ (0.02)	$ 0.65	$ 0.56
Net income per share – diluted (in USD per share)	$ 0.10	$ (0.02)	$ 0.64	$ 0.55