Stock-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares available for issuance	2,200,000		2,200,000
Compensation cost	$ 1.9	$ 1.7	$ 5.3	$ 4.7
Income tax benefit recognized in the income statement for stock-based awards	0.6	0.8	1.5	1.6
Weighted-average fair value per option granted			$ 7.87
Total cash received as a result of stock option exercises			10.4	3.5
Tax benefit realized as a result of stock option exercises and the vesting of other share-based awards			1.8	0.9
Total intrinsic value of stock options exercised			$ 2.9	$ 1.2
Employee Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years
Contractual life of options			10 years
Stock options issued	0	1,000	348,000	431,000
Non-Employee Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year

Contractual Life Of Options

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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 total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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- Definition

Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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- Definition

The total cash inflow associated with the amount received from holders to acquire the entity's shares under incentive and share awards, including stock option exercises. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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-Glossary Financing Activities

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- Definition

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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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Number of share instruments newly issued under a share-based compensation plan.

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