Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of Options
Beginning balance (in shares)	3,547,913
Granted (in shares)	653,900	540,548
Exercised (in shares)	(561,015)
Forfeited (in shares)	(91,261)
Expired (in shares)	(2,009)
Ending balance (in shares)	3,547,528	3,547,913
Weighted Average Exercise Price Per Share
Beginning balance (USD per share)	$ 4.17
Granted (USD per share)	17.87
Exercised (USD per share)	1.88
Forfeited (USD per share)	9.45
Expired (USD per share)	9.79
Ending balance (USD per share)	$ 6.91	$ 4.17
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Outstanding, weighted average remaining contractual life (in years)	6 years 4 months 24 days	6 years 7 months 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value [Roll Forward]
Outstanding, beginning balance, aggregate intrinsic value	$ 44,411
Aggregate intrinsic value of stock options exercised during period	14,114	$ 3,300	$ 7,300
Outstanding, ending balance, aggregate intrinsic value	$ 74,267	$ 44,411
Vested and expected to vest (in shares)	3,502,351
Vested and expected to vest, weighted average exercise (USD per share)	$ 6.81
Vested and expected to vest, weighted average remaining contractual life (in years)	6 years 4 months 24 days
Vested and expected to vest, aggregate intrinsic value	$ 73,621
Exercisable (in shares)	2,144,142
Exercisable, weighted average exercise (USD per share)	$ 3.36
Exercisable, weighted average remaining contractual life (in years)	5 years 2 months 12 days
Exercisable, aggregate intrinsic value	$ 52,460
Weighted average grant date fair value for stock options (USD per share)	$ 8.77	$ 5.90	$ 4.20
Fair value of stock options vested during period	$ 2,200	$ 2,700	$ 1,500
Compensation cost not yet recognized on nonvested awards	$ 4,500

Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value [Roll Forward]

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Unrecognized cost of unvested options awarded to employees as compensation.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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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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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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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 of difference between fair value of the underlying shares reserved for issuance and exercise price of fully vested and expected to vest options that are exercisable.

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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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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 of the plan that expired.

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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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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 that are 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 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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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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

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