Share Based Compensation (Summary of Share Incentive Plans) (Details) (USD $)	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010
Share-Based Compensation
Outstanding Options, Number	1,837,990
Weighted average exercise/grant price, balance at December 31, 2010	$ 42.39
Granted, options outstanding	0
Granted, weighted average exercise/grant price	$ 0.00
Exercised/Vested, option outstanding	(327,454)	(100,000)
Exercised/Vested, weighted average exercise/grant price	$ 42.89
Forfeited, options outstanding	0
Forfeited, weighted average exercise/grant price	$ 0.00
Net activity, option outstanding	(327,454)
Outstanding Options, Number	1,510,536
Weighted average exercise/grant price, balance at June 30, 2011	$ 42.29
Nonvested share awards outstanding at December 31, 2010, share awards outstanding	741,505
Nonvested share awards outstanding at December 31, 2010, weighted average exercise/grant price	$ 42.16
Granted, share awards outstanding	339,143
Granted, weighted average exercise/grant price	$ 56.92
Exercised/Vested, share awards outstanding	(235,083)
Exercised/Vested, weighted average exercise/grant price	$ 46.74
Forfeited, share awards outstanding	(11,626)
Forfeited, weighted average exercise/grant price	$ 42.76
Net activity, share awards outstanding	92,434
Nonvested share awards outstanding at June 30, 2011, share awards outstanding	833,939
Nonvested share awards outstanding at June 30, 2011, weighted average exercise/grant price	$ 46.86

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

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The number of shares under a share-based award plan other than a stock option plan that were settled during the reporting period due to a failure to satisfy vesting conditions pertaining to all option plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Statement of Financial Accounting Standard (FAS)
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-Paragraph A240
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The weighted average fair value as of the grant date of share-based award plans other than stock option plans that were not exercised or put into effect during the reporting period as a result of the occurrence of a terminating event specified in the contractual agreement of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The number of shares issuable under a share-based award plan pertaining to grants made during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan).

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The weighted average fair value at grant for nonvested share-based awards issued during the period on other than stock option plans (for example, phantom stock plan, stock appreciation rights plan, performance target plan).

+ References

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The number of outstanding awards on nonstock option plans (for example, phantom stock plan, stock appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares.

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The weighted average fair value of nonvested awards on share-based plans excluding option plans (for example, phantom stock plan, stock appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares.

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The net total number of shares under a share-based award plan, other than a stock option plan, that were granted, vested and forfeited during the reporting period.

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The decrease in the number of shares potentially issuable under a share-based award plan pertaining to awards for which the grantee has gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares, other instruments, or cash in accordance with the terms of the arrangement.

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The weighted average fair value as of grant dates pertaining to a share-based award plan other than a stock option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares, other instruments, or cash in accordance with the terms of the arrangement.

+ References

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The decrease in the number of reserved shares that could potentially be issued attributable to the exercise or conversion during the reporting period of previously issued stock options under the option plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

+ References

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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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The quantity of shares issuable on stock options awarded under the plan during the reporting 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
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The increase or decrease in number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding, including vested options.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ References

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