Stock-Based Compensation (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Summary of stock options outstanding and related information
Beginning Balance, Options	10,902
Beginning Balance, Weighted Average Exercise Price Per Option	$ 50.72
Granted, Options	1,281
Granted, Weighted Average Exercise Price Per Option	$ 68.94
Exercised, Options	(2,636)
Exercised, Weighted Average Exercise Price Per Option	$ 43.05
Forfeited, Options	(78)
Forfeited, Weighted Average Exercise Price Per Option	$ 52.29
Expired, Options	(37)
Expired, Weighted Average Exercise Price Per Option	$ 59.10
Ending Balance, Options	9,432
Ending Balance, Weighted Average Exercise Price Option	$ 55.34

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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The decrease in the number of shares that could be issued attributable to the lapse of rights to exercise previously issued stock options under the terms of the option agreements under the plan during the reporting period.

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The weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that lapsed during the reporting period.

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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.

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The weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated during the reporting period due to noncompliance with plan terms during the reporting period.

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

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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 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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