Equity-Based Compensation Plans (Details 1) (Stock Options, USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Stock Options
Weighted Average Exercise Price
Balance, beginning	$ 17.80
Granted
Exercised
Forfeited
Expired
Outstanding	$ 17.80
Exercisable	$ 19.15
Number of shares:
Balance options outstanding, beginning	521,613
Granted
Exercised
Forfeited
Expired
Balance options outstanding, end	521,613
Exercisable, end of period	445,613
Weighted- Average Contractual Term (years), outstanding	3 years 8 months
Weighted- Average Contractual Term (years), exercisable	2 years 8 months
Aggregate Intrinsic Value, exercisable
Aggregate Intrinsic Value, outstanding	$ 279,750

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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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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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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Weighted average price of options that were either forfeited or expired.

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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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Gross number of share options (or share units) granted during the 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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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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