Equity Incentive Plans - Schedule of Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Stock options outstanding (in shares)	1,752,156	1,752,156
Stock options granted (in shares)	0
Stock options exercised (in shares)	(1,752,156)	(198,026)
Stock options exercised (in shares)	0	1,752,156
Weighted Average Exercise Price
Stock options outstanding, beginning balance (in usd per share)	$ 12.30
Stock options granted (in usd per share)	0.00
Stock options exercised (in usd per share)	12.30
Stock options outstanding, ending balance (in usd per share)	$ 0.00	$ 12.30
Stock options outstanding, weighted average remaining contractual term	1 day	5 months 23 days
Stock options outstanding, aggregate intrinsic value	$ 0	$ 4,422

Stock Options Outstanding

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- Definition

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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- Definition

Gross number of share options (or share units) granted during the period.

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- Definition

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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- Definition

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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- Definition

Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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- Definition

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

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- Definition

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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- Definition

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

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