Equity Incentive Plans Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock options outstanding, shares	1,511,304	1,738,073
Stock options exercised, shares	(226,260)
Stock options forfeited/canceled, shares	(509)
Exercisable stock options, shares	1,511,304
Stock options outstanding, weighted average exercise price	$ 9.08	$ 9.20
Stock options exercised, weighted average exercise price	9.97
Stock options forfeited/canceled, weighted average exercise price	32.31
Exercisable stock options, weighted average exercise price	$ 9.08
Stock options outstanding, weighted average remaining contractual term (years)	1 year 4 months 24 days
Exercisable stock options, weighted average remaining contractual term (years)	1 year 4 months 24 days
Stock options exercised, aggregate intrinsic value	$ 7,123
Stock options outstanding, aggregate intrinsic value	43,631
Exercisable stock options, aggregate intrinsic value	$ 43,631

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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-Publisher FASB
-Name Accounting Standards Codification
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Weighted average price of options that were either forfeited or expired.

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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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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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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 reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

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Number of non-vested options forfeited.

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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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