Accounting For Stock Based Compensation (Details 4) (USD $)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Beginning Balance, Shares	2,125,291	1,897,541	1,684,207
Granted, Shares	1,109,949	1,099,000	1,188,814
Vested, Shares	(1,009,959)	(860,749)	(965,478)
Forfeited, Shares	17,669	10,501	10,002
Ending Balance, Shares	2,207,612	2,125,291	1,897,541
Beginning of Period, Weighted Average Grant Date Fair Value	$ 27.92	$ 24.09	$ 35.57
Granted, Weighted Average Grant Date Fair Value	$ 37.57	$ 33.83	$ 18.45
Vested, Weighted Average Grant Date Fair Value	$ 27.40	$ 27.04	$ 37.08
Forfeited, Weighted Average Grant Date Fair Value	$ 35.68	$ 27.84	$ 32.52
End of Period, Weighted Average Grant Date Fair Value	$ 32.95	$ 27.92	$ 24.09
Phantom Stock and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Beginning Balance, Shares	53,388	50,057	0
Vested, Shares	(22,560)	(21,449)
Forfeited, Shares
Ending Balance, Shares	52,956	53,388	50,057
Beginning of Period, Weighted Average Grant Date Fair Value	$ 26.11	$ 19.19	$ 0.00
Vested, Weighted Average Grant Date Fair Value	$ 24.68	$ 18.97
Forfeited, Weighted Average Grant Date Fair Value
End of Period, Weighted Average Grant Date Fair Value	$ 31.67	$ 26.11	$ 19.19
Phantom stock [Member] \| Phantom Stock and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Granted, Shares			42,906
Granted, Weighted Average Grant Date Fair Value			$ 18.18
Restricted Stock Units [Member] \| Phantom Stock and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Granted, Shares	22,128	24,780	7,151
Granted, Weighted Average Grant Date Fair Value	$ 37.96	$ 33.90	$ 25.27

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

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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- Definition

The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit 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 or units.

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- Definition

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

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