Stock-Based Compensation - Stock Option Activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Number of Shares
Beginning stock options outstanding (in shares)	2,071,757	2,283,785	2,128,904
Granted (in shares)	233,828	35,081	262,051
Exercised (in shares)	(143,282)	(155,731)	(56,658)
Forfeited (in shares)	(105,405)	(91,378)	(50,512)
Ending stock options outstanding (in shares)	2,056,898	2,071,757	2,283,785
Weighted Average Exercise Price Per Share
Beginning stock options outstanding (in dollars per share)	$ 9.49	$ 9.23	$ 9.42
Granted (in dollars per share)	$ 11.35	$ 9.48	$ 6.56
Exercised (in dollars per share)	$ 6.08	$ 5.51	$ 5.27
Forfeited (in dollars per share)	$ 11.06	$ 9.82	$ 7.99
Ending stock options outstanding (in dollars per share)	$ 9.86	$ 9.49	$ 9.23
December 31, 2014
Number of Shares	2,031,492
Weighted Average Exercise Price Per Share (in dollars per share)	$ 9.87
Weighted Average Contractual Life	5 years 9 months 22 days
Aggregate Intrinsic Value	$ 5,360
December 31, 2014
Number of Shares	1,461,837
Weighted Average Exercise Price Per Share (in dollars per share)	$ 10.50
Weighted Average Contractual Life	4 years 11 months 16 days
Aggregate Intrinsic Value	$ 3,681

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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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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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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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Amount by which the current fair value of the underlying stock exceeds the exercise price 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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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 that were terminated.

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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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