Shared-Based Compensation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Reconciliation of option activity
Number of options, Outstanding, Beginning Balance	1,384
Weighted-Average Exercise Price, Outstanding, Beginning Balance	$ 9.94
Number of Options, Granted	254	278
Weighted-Average Exercise Price, Granted	$ 9.97
Number of Options, Exercised
Weighted-Average Exercise Price, Exercised
Number of Options, Forfeited or expired	(9)
Weighted-Average Exercise Price, Forfeited or expired	$ 9.36
Number of options, Outstanding, Ending Balance	1,629
Weighted-Average Exercise Price, Outstanding, Ending Balance	$ 9.95
Weighted-Average Remaining Contractual Term, Outstanding, Ending Balance	6 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 1,732
Number of Options, Options Exercisable	1,071
Weighted-Average Exercise Price, Options exercisable	$ 9.69
Weighted- Average Remaining Contractual Term Exercised	4 years 4 months 24 days
Aggregate Intrinsic Value Exercisable	$ 1,617

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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For presentations that combine terminations, 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 or that expired.

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

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

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