Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Computation of Earnings Per Share (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended
Computation of Earnings Per Share (Details) (USD $)	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013	Sep. 28, 2012	Sep. 27, 2013 Equity awards granted to employees [Member]	Sep. 28, 2012 Equity awards granted to employees [Member]	Sep. 27, 2013 Equity awards granted to employees [Member]	Sep. 28, 2012 Equity awards granted to employees [Member]	Nov. 30, 2010 Convertible Debt Securities [Member] Convertible Debt [Member]	Sep. 27, 2013 Warrant [Member]	Sep. 28, 2012 Warrant [Member]	Sep. 27, 2013 Warrant [Member]	Sep. 28, 2012 Warrant [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Earnings from continuing operations	$ 18,695,000	$ 14,784,000	$ 43,741,000	$ 39,994,000
Earnings from discontinued operations, net of taxes	64,000	198,000	64,000	870,000
Gain on disposal of discontinued operations, net of taxes	420,000	0	420,000	0
Net earnings	19,179,000	14,982,000	44,225,000	40,864,000
Weighted Average Number of Shares Outstanding, Basic	26,770,000	26,455,000	26,721,000	26,380,000
Basic earnings per share from continuing operations	$ 0.70	$ 0.56	$ 1.64	$ 1.52
Basic earnings per share from discontinued operations	$ 0.00	$ 0.01	$ 0.00	$ 0.03
Basic earnings per share from disposal of discontinued operations	$ 0.02	$ 0.00	$ 0.02	$ 0.00
Basic earnings per share	$ 0.72	$ 0.57	$ 1.66	$ 1.55
Weighted average shares issuable on exercise of dilutive stock options	164,000	168,000	156,000	160,000
Weighted average shares issuable on exercise of convertible notes	299,000	0	185,000	0
Weighted Average Number of Shares Outstanding, Diluted	27,233,000	26,623,000	27,062,000	26,540,000
Diluted earnings per share from continuing operations	$ 0.68	$ 0.55	$ 1.61	$ 1.51
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share	$ 0.00	$ 0.01	$ 0.00	$ 0.03
Diluted earnings per share from disposal of discontinued operations	$ 0.02	$ 0.00	$ 0.02	$ 0.00
Diluted earnings per share	$ 0.70	$ 0.56	$ 1.63	$ 1.54
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount					405,505	336,893	429,541	351,103		3,405,585	3,397,902	3,403,710	3,395,861
Convertible Notes, Face Amount									$ 115,000,000