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. 26, 2014	Sep. 27, 2013	Sep. 26, 2014	Sep. 27, 2013	Sep. 26, 2014 Equity awards granted to employees [Member]	Sep. 27, 2013 Equity awards granted to employees [Member]	Sep. 26, 2014 Equity awards granted to employees [Member]	Sep. 27, 2013 Equity awards granted to employees [Member]	Nov. 30, 2010 Convertible Debt Securities [Member] Convertible Debt [Member]	Sep. 26, 2014 Warrant [Member]	Sep. 27, 2013 Warrant [Member]	Sep. 26, 2014 Warrant [Member]	Sep. 27, 2013 Warrant [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Earnings from continuing operations	$ 14,873,000	$ 18,695,000	$ 42,524,000	$ 43,741,000
Earnings from discontinued operations, net of tax	(94,000)	64,000	285,000	64,000
Earnings from discontinued operations, net of taxes	(94,000)	484,000	285,000	484,000
Gain on disposal of discontinued operations, net of taxes	0	420,000	0	420,000
Net earnings	14,779,000	19,179,000	42,809,000	44,225,000
Weighted Average Number of Shares Outstanding, Basic	27,113,000	26,770,000	27,025,000	26,721,000
Basic earnings per share from continuing operations	$ 0.55	$ 0.70	$ 1.57	$ 1.64
Basic earnings per share from discontinued operations	$ 0.00	$ 0.00	$ 0.01	$ 0.00
Basic earnings per share from disposal of discontinued operations	$ 0.00	$ 0.02	$ 0.00	$ 0.02
Basic earnings per share	$ 0.55	$ 0.72	$ 1.58	$ 1.66
Weighted average shares issuable on exercise of dilutive stock options	142,000	164,000	152,000	156,000
Weighted average shares issuable on exercise of convertible notes	607,000	299,000	589,000	185,000
Weighted Average Number of Shares Outstanding, Diluted	27,862,000	27,233,000	27,766,000	27,062,000
Diluted earnings per share from continuing operations	$ 0.53	$ 0.68	$ 1.53	$ 1.61
Diluted earnings per share from discontinued operations	$ 0.00	$ 0.00	$ 0.01	$ 0.00
Diluted earnings per share from disposal of discontinued operations	$ 0.00	$ 0.02	$ 0.00	$ 0.02
Diluted earnings per share	$ 0.53	$ 0.70	$ 1.54	$ 1.63
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount					310,192	405,505	356,841	429,541		3,412,339	3,405,585	3,410,690	3,403,710
Convertible Notes, Face Amount									$ 115,000,000