Share-Based Compensation - Stock Option Activity (Details) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Beginning balance (in shares)	442,012
Exercised (in shares)	(128,848)
Canceled (in shares)	(52,953)
Ending balance (in shares)	260,211	442,012
Vested and Expected to Vest, Number of Shares	260,211
Exercisable, Number of Shares	260,211
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 19.99	$ 20.99
Exercised (in dollars per share)	19.37
Canceled (in dollars per share)	25.09
Ending balance (in dollars per share)	19.26	$ 19.99
Vested and Expected to Vest, Weighted-Average Exercise Price (in dollars per share)	19.26
Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 19.26
Weighted Average Remaining Contractual Term
Outstanding	2 years 8 months 16 days
Vested and Expected to Vest	2 years 8 months 16 days
Exercisable	2 years 8 months 16 days
Aggregate Intrinsic Value
Outstanding	$ 4,785,982
Vested and Expected to Vest	4,785,982
Exercisable	$ 4,785,982

Share-based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value [Abstract]

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Share-based Compensation Arrangement by Share-based Payment Award, Options, Weighted Average Remaining Contractual Term [Abstract]

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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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-Publisher FASB
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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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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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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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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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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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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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 remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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