Share-Based Compensation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011 Y
Summary of stock option activity
Stock Options, Beginning balance	3,323
Stock Options, Granted	894
Stock Options, Exercised	(395)
Stock option, Forfeited/Canceled	(46)
Stock Options, Ending balance	3,776
Stock Options, Exercisable	2,543
Stock Options, Vested and Expected to Vest	3,720
Weighted-Average Exercise Price, Beginning balance	$ 16.45
Weighted-Average Exercise Price, Granted	$ 15.98
Weighted-Average Exercise Price, Exercised	$ 10.12
Weighted-Average Exercise Price, Forfeited/Canceled	$ 23.25
Weighted-Average Exercise Price, Ending balance	$ 16.92
Weighted-Average Exercise Price, Exercisable	$ 17.23
Weighted-Average Exercise Price, Vested and expected to vest	$ 16.93
Weighted-Average Remaining Contractual Term (Years), Outstanding	2.3
Weighted-Average Remaining Contractual Term (Years), Exercisable	1.1
Weighted-Average Remaining Contractual Term (Years), Vested and expected to vest	2.2
Aggregate Intrinsic Value, Outstanding	$ 10,699
Aggregate Intrinsic Value, Exercisable	6,409
Aggregate Intrinsic Value, Vested and expected to vest	$ 4,097

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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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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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