Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 26, 2014	Sep. 26, 2014	Jun. 27, 2014	Mar. 28, 2014	Dec. 27, 2013	Sep. 27, 2013	Jun. 28, 2013	Mar. 29, 2013	Dec. 26, 2014	Dec. 27, 2013	Dec. 28, 2012
Earnings Per Share Details [Abstract]
Net earnings available to common shareholders	$ 49,041	$ 59,551	$ 66,236	$ 50,745	$ 44,748	$ 56,101	$ 57,843	$ 52,130	$ 225,573	$ 210,822	$ 149,126
Weighted average shares outstanding for basic earnings per share									60,148	61,203	60,451
Dilutive effect of stock options computed based on the treasury stock method using the average market price									1,597	1,587	1,260
Weighted average shares outstanding for diluted earnings per share									61,745	62,790	61,711
Basic earnings per share	$ 0.83us-gaap_EarningsPerShareBasic	$ 0.99us-gaap_EarningsPerShareBasic	$ 1.10us-gaap_EarningsPerShareBasic	$ 0.83us-gaap_EarningsPerShareBasic	$ 0.73us-gaap_EarningsPerShareBasic	$ 0.91us-gaap_EarningsPerShareBasic	$ 0.94us-gaap_EarningsPerShareBasic	$ 0.86us-gaap_EarningsPerShareBasic	$ 3.75us-gaap_EarningsPerShareBasic	$ 3.44us-gaap_EarningsPerShareBasic	$ 2.47us-gaap_EarningsPerShareBasic
Diluted earnings per share	$ 0.80us-gaap_EarningsPerShareDiluted	$ 0.97us-gaap_EarningsPerShareDiluted	$ 1.07us-gaap_EarningsPerShareDiluted	$ 0.81us-gaap_EarningsPerShareDiluted	$ 0.71us-gaap_EarningsPerShareDiluted	$ 0.89us-gaap_EarningsPerShareDiluted	$ 0.92us-gaap_EarningsPerShareDiluted	$ 0.84us-gaap_EarningsPerShareDiluted	$ 3.65us-gaap_EarningsPerShareDiluted	$ 3.36us-gaap_EarningsPerShareDiluted	$ 2.42us-gaap_EarningsPerShareDiluted
Antidilutive options excluded from computation									600,000	400,000	600,000

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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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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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