Computation of Earnings Per Share (Details) - USD ($)	3 Months Ended
	Apr. 01, 2016	Apr. 03, 2015	Nov. 30, 2010
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net earnings	$ 9,777,000	$ 12,749,000
Weighted Average Number of Shares Outstanding, Basic	27,059,000	27,188,000
Basic earnings per share	$ 0.36	$ 0.47
Weighted average shares issuable on exercise of dilutive stock options	135,000	137,000
Weighted average shares issuable on exercise of convertible notes	612,000	553,000
Weighted Average Number of Shares Outstanding, Diluted	27,806,000	27,878,000
Diluted earnings per share	$ 0.35	$ 0.46
Equity awards granted to employees [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	663,302	501,263
Convertible Debt Securities [Member] | Convertible Debt [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Convertible Notes, Face Amount			$ 115,000,000
Warrant [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,430,992	3,417,392