Net Loss Per Share (EPS) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic earnings per common share:
Net (loss) income	$ (17,630)	$ 3,724	$ (47,315)	$ (6,406)
Less: Noncumulative dividends on convertible preferred stock		(2,552)
Undistributed earnings to participating securities		(1,000)
Net (loss) income attributable to common shares, basic	$ (17,630)	$ 172	$ (47,315)	$ (6,406)
Weighted-average common shares outstanding	46,380	6,689	20,252	6,646
Less: weighted-average unvested common shares subject to repurchase	(1,436)	(1,823)	(1,531)	(1,918)
Weighted-average number of shares used in computing net loss per share, basic	44,944	4,866	18,721	4,728
Basic net (loss) income per share	$ (0.39)	$ 0.04	$ (2.53)	$ (1.35)
Diluted earnings per common share:
Net (loss) income attributable to common shares, basic	$ (17,630)	$ 172	$ (47,315)	$ (6,406)
Adjustment to undistributed earnings to participating securities		1,000
Net (loss) income attributable to common shares, diluted	$ (17,630)	$ 1,172	$ (47,315)	$ (6,406)
Weighted-average number of shares used in computing net loss per share, basic	44,944	4,866	18,721	4,728
Add: Weighted average number of potential dilutive common shares		32,065
Weighted-average number of shares unused in computing net loss per share, diluted	44,944	36,931	18,721	4,728
Diluted net (loss) income per share (in dollars per share)	$ (0.39)	$ 0.03	$ (2.53)	$ (1.35)