Share-Based Awards, Purchase Plans and Compensation Cost (Narratives) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 26, 2014	Dec. 27, 2013	Dec. 28, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 17.2	$ 16.5	$ 12.4
Intrinsic value of exercisable option shares	154.5
Exercisable option weighted average contractual term	4 years 7 months
Share options vested and expected to vest	4,900,000
Aggregate intrinsic value of share options vested and expected to vest	182.2
Weighted average exercise price of share options vested and expected to vest (per share)	$ 44.50
Weighted average contractual term of share options vested and expected to vest	5 years 10 months
Employee stock purchase plan shares granted	193,084	196,913	238,621
Share-based compensation impact on net income	12.8	12.6	9.5
Share-based compenstion impact on EPS	$ 0.21	$ 0.20	$ 0.15
Unrecognized compensation cost related to unvested options	13.7
Weighted average recognition period for unvested options	1 year 7 months
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	1.0	1.9	0.5
Stock Incentive Plan (2010)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period	10 years
Stock Incentive Plan (2010) \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Stock Incentive Plan (2010) \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Stock Incentive Plan (2010) \| Nonemployee Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued under the plan	4,867	6,079	7,656
Stock Incentive Plan (2010) \| Restricted Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 0.3	$ 0.5	$ 0.4
Employee Stock Purchase Plan (2006)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share purchase price as percentage of fair value	85.00%
Stock purchase plan discount percentage	15.00%

The effect that share-based compensation expenses have on earnings per share.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The amount of expense, net of income tax, recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Number of shares issued pursuant to the terms of a deferred compensation arrangement.

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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Discount rate from fair value on offering date that participants pay for shares.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Purchase price of common stock expressed as a percentage of its fair value.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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