Basic and Diluted Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Ordinary Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net loss attributable to ordinary shares as reported	$ (10,945)	$ (11,498)	$ (21,174)	$ (18,045)	$ (22,168)	$ (33,628)	$ (40,612)	$ (35,437)	$ (61,662)	$ (131,845)	$ (111,581)
Shares used in computing net loss per ordinary share, basic and diluted	89,389,364	89,125,646	88,218,868	87,452,983	86,760,316	85,774,874	85,274,683	84,397,164	88,546,719	85,558,448	30,401,603
Net loss per ordinary share, basic and diluted	$ (0.12)	$ (0.13)	$ (0.24)	$ (0.21)	$ (0.26)	$ (0.39)	$ (0.48)	$ (0.42)	$ (0.70)	$ (1.54)	$ (3.67)