Equity Incentive Plans - Summary of Activity Related to Outstanding Stock Options (Details)	3 Months Ended
Mar. 31, 2019 $ / shares shares
Service Period Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Outstanding Beginning Balance \| shares	1,793,981
Shares, Exercised \| shares	(248,195)
Shares, Outstanding Ending Balance \| shares	1,545,786
Weighted Average Exercise Price, Outstanding Beginning Balance \| $ / shares	$ 9.84
Weighted Average Exercise Price, Exercised \| $ / shares	7.22
Weighted Average Exercise Price, Outstanding Ending Balance \| $ / shares	$ 10.26
Performance-Vested Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Outstanding Beginning Balance \| shares	1,275,746
Shares, Forfeited \| shares	(39,253)
Shares, Outstanding Ending Balance \| shares	1,236,493
Weighted Average Exercise Price, Outstanding Beginning Balance \| $ / shares	$ 13.62
Weighted Average Exercise Price, Forfeited \| $ / shares	9.05
Weighted Average Exercise Price, Outstanding Ending Balance \| $ / shares	$ 13.77
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Outstanding Beginning Balance \| shares	271,979
Shares, Granted \| shares	6,888
Shares, Issued upon vesting \| shares	(79,883)
Shares, Forfeited \| shares	(168)
Shares, Outstanding Ending Balance \| shares	198,816
Weighted-Average Grant-Date Fair Value Per Unit, Outstanding Beginning Balance \| $ / shares	$ 19.07
Weighted-Average Grant-Date Fair Value Per Unit, Granted \| $ / shares	35.96
Weighted-Average Grant-Date Fair Value Per Unit, Issued Upon Vesting \| $ / shares	21.75
Weighted-Average Grant-Date Fair Value Per Unit, Forfeited \| $ / shares	35.96
Weighted-Average Grant-Date Fair Value Per Unit, Outstanding Ending Balance \| $ / shares	$ 18.56

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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- Definition

The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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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- Definition

Number of options outstanding, including both vested and non-vested options.

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

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- Definition

Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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- Definition

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

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