Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net loss	$ (73,719)	$ (37,796)	$ (200,698)	$ (103,086)
Denominator:
Weighted average common stock outstanding—basic	37,470,912	32,975,897	37,367,802	32,218,204
Dilutive effect of shares of common stock equivalents resulting from common stock options and restricted stock units	0	0	0	0
Weighted average common stock outstanding—diluted	37,470,912	32,975,897	37,367,802	32,218,204
Net loss per share—basic and diluted	$ (1.97)	$ (1.15)	$ (5.37)	$ (3.20)