Net Loss per Share - Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net loss used to compute net loss per share, basic	$ (32,873)	$ (33,480)
Less: Remeasurement gain on warrant liability		(1,042)
Net loss used to compute net loss per share, diluted	$ (32,873)	$ (34,522)
Denominator:
Weighted-average number of shares used in computing net loss per share, basic	54,132	52,758
Add: incremental shares from assumed exercise of warrants		285
Weighted-average number of shares used in computing net loss per share, basic and diluted	54,132	53,043
Net loss per share, basic (in dollars per share)	$ (0.61)	$ (0.63)
Net loss per share, diluted (in dollars per share)	$ (0.61)	$ (0.65)

Represents the remeasurement gain on warrant liability during the period.

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- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of call options and warrants using the treasury stock method.

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- Definition

Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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- Definition

Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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- Definition

Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

+ References

No definition available.

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- Definition

This element represents the weighted average total number of shares issued throughout the period including the first (beginning balance outstanding) and last (ending balance outstanding) day of the period before considering any reductions (for instance, shares held in treasury) to arrive at the weighted average number of shares outstanding. Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic).

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