Computation of Earnings Per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017
Earnings Per Share Reconciliation [Abstract]
Net earnings	$ 15,094	$ 13,458	$ 29,160	$ 19,749
Basic:
Weighted average number of shares outstanding (in shares)	27,971	27,557	27,911	27,351
Basic earnings per share (in usd per share)	$ 0.54	$ 0.49	$ 1.04	$ 0.72
Diluted:
Weighted average shares issuable on exercise of dilutive stock options (in shares)	237	141	228	154
Weighted average shares issuable on redemption of 2017 Notes (in shares)	108	108	54	628
Weighted average shares issuable on redemption of warrants related to the 2017 Notes (in shares)	33	36	65	237
Diluted (in shares)	28,349	27,842	28,258	28,370
Diluted earnings per share (in usd per share)	$ 0.53	$ 0.48	$ 1.03	$ 0.70