Stock Based Compensation (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	5.0	5.6	6.0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	0.1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	(0.5)	(0.2)	(0.2)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period	(0.6)	(0.4)	(0.3)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	3.9	5.0	5.6
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	$ 0.4
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 0.00	$ 0.00	$ 2.81
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 8.69	$ 6.94	$ 4.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 26.96	$ 17.37	$ 22.84
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 26.95	$ 25.01	$ 23.96	$ 23.57
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	3.8	4.8	5.1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 27.25	$ 25.75	$ 25.05
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 3.0	$ 0.8

Description of the period of time over 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, which may be expressed in a variety of ways (for example, in years, month and year).

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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- Definition

The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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- Definition

The combined weighted average exercise price associated with stock options during the period that have either lapsed or been forfeited.

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Gross number of share options (or share units) granted during the period.

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No definition available.

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The weighted average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period.

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The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices pertaining to options outstanding under the plan as of the balance sheet date.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Number of share options (or share units) exercised during the current period.

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