Share-Based Compensation (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair value of restricted stock shares and units is the market price of our common stock on the date of grant
Exercised or converted, Aggregate Intrinsic Value	$ 3,801	$ 2,947	$ 128
Granted, Weighted- Average Grant-Date Fair Value	$ 35.91	$ 22.34	$ 13.80
Stock Appreciation Rights and Stock Options [Member]
Fair value of restricted stock shares and units is the market price of our common stock on the date of grant
Outstanding number, Beginning balance	3,043
Outstanding, Weighted-Average Exercise Price, Beginning balance	$ 25.26
Outstanding, Weighted- Average Remaining Contractual Term, Beginning balance	0.0
Outstanding, Aggregate Intrinsic Value, Beginning balance	0
Granted, number	538
Granted, Weighted-Average Exercise Price	$ 35.79
Granted, Aggregate Intrinsic Value	0
Exercised or converted, number	(346)
Exercised or converted, Weighted-Average Exercise Price	$ 19.52
Exercised or converted, Aggregate Intrinsic Value	0
Forfeited or expired, Number	(111)
Forfeited or expired, Weighted-Average Exercise Price	$ 34.98
Forfeited or expired, Aggregate Intrinsic Value	0
Vested or expected, Aggregate Intrinsic Value	18,541
Outstanding number, Ending balance	3,124
Outstanding, Aggregate Intrinsic Value, Ending balance	18,473
Outstanding, Weighted-Average Exercise Price, Ending balance	$ 27.37
Outstanding, Weighted- Average Remaining Contractual Term, Ending balance	6.4
Vested or expected, Number	3,097
Vested or expected, Weighted-Average Exercise Price	$ 27.37
Vested or expected, Weighted- Average Remaining Contractual Term	6.4
Exercisable or convertible, Number	1,751
Exercisable or convertible, Weighted-Average Exercise Price	$ 26.85
Exercisable or convertible, Weighted- Average Remaining Contractual Term	5.2
Exercisable or convertible, Aggregate Intrinsic Value	$ 11,265
Restricted Stock Units (RSUs) [Member]
Fair value of restricted stock shares and units is the market price of our common stock on the date of grant
Granted (RSUs), Number	91
Exercised or converted (RSUs), Number	(197)
Forfeited or expired (RSUs), Number	(35)
Exercised or converted, Weighted- Average Grant-Date Fair Value	$ 21.78
Forfeited or expired, Weighted- Average Grant-Date Fair Value	$ 19.47
Granted, Weighted- Average Grant-Date Fair Value	$ 35.91
Outstanding, Weighted- Average Grant-Date Fair Value, Ending balance	$ 23.11	$ 20.96
Outstanding number (RSUs), Beginning balance	723
Outstanding number (RSUs), Ending balance	582

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Share based compensation arrangement by share based payment award options forfeitures and expirations intrinsic value.

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Share based compensation arrangement by share based payment award options granted intrinsic value.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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The weighted average fair value as of the grant date of equity-based award plans other than stock (unit) 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.

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The number of grants made 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 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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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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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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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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The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of vested portions of options outstanding and currently exercisable under the option plan as of the balance sheet date.

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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.

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The weighted average period between the balance sheet date and expiration for all vested portions of options outstanding and currently exercisable (or convertible) under the plan, which may be expressed in a decimal value for number of years.

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

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

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Number of share options (or share units) forfeited 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 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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The weighted average period between the balance sheet date and expiration for all awards outstanding under the plan, which may be expressed in a decimal value for number of years.

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As of the balance sheet date, the total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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

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