Share-Based Compensation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Summary of stock option activity
Stock options, Beginning balance (shares)	1,031	2,181
Stock options, Granted (shares)	0	0
Stock options, Exercised (shares)	(177)	(1,043)
Stock options, Expired (shares)	0	(36)
Stock options, Forfeited/Canceled (shares)	(9)	(71)
Stock options, Ending balance (shares)	845	1,031
Stock Options, Exercisable (shares)	414
Stock options, Vested and expected to vest (shares)	836
Weighted-Average Exercise Price, Beginning balance (in dollars per share)	$ 17.28	$ 17.20
Weighted-Average Exercise Price, Granted (in dollars per share)	$ 0.00	$ 0.00
Weighted-Average Exercise Price, Exercised (in dollars per share)	$ 16.12	$ 16.73
Weighted-Average Exercise Price, Expired (in dollars per share)	$ 0.00	$ 30.70
Weighted-Average Exercise Price, Forfeited/Canceled (in dollars per share)	$ 15.98	$ 16.06
Weighted-Average Exercise Price, Ending balance (in dollars per share)	$ 17.54	$ 17.28
Weighted-Average Exercise Price, Exercisable (in dollars per share)	$ 17.51
Weighted-Average Exercise Price, Vested and expected to vest (in dollars per share)	$ 17.56
Weighted-Average Remaining Contractual Term (Years), Outstanding	2 years 256 days	3 years 256 days
Weighted-Average Remaining Contractual Term (Years), Exercisable	2 years 256 days
Weighted-Average Remaining Contractual Term (Years), Vested and expected to vest	2 years 256 days
Aggregate Intrinsic Value, Outstanding	$ 26,400	$ 14,516
Aggregate Intrinsic Value, Exercisable	12,952
Aggregate Intrinsic Value, Vested and expected to vest	$ 26,105

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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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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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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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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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The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date.

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As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest.

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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 per share amount at which grantees can acquire shares of common stock by exercise of options.

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