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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	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, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income (loss) attributable to ordinary shares as reported	$ (15,631)	$ (11,694)	$ (15,510)	$ (20,724)	$ (10,945)	$ (11,498)	$ (21,174)	$ (18,045)	$ (22,168)	$ (33,628)	$ (40,612)	$ (35,437)	$ (63,559)	$ (61,662)	$ (131,845)
Shares used in computing net income (loss) per ordinary share, basic and diluted	93,083,298	92,911,375	91,331,862	89,985,612	89,389,364	89,125,646	88,218,868	87,452,983	86,760,316	85,774,874	85,274,683	84,397,164	91,828,043	88,546,719	85,558,448
Net income (loss) per ordinary share, basic and diluted	$ (0.17)	$ (0.13)	$ (0.17)	$ (0.23)	$ (0.12)	$ (0.13)	$ (0.24)	$ (0.21)	$ (0.26)	$ (0.39)	$ (0.48)	$ (0.42)	$ (0.69)	$ (0.70)	$ (1.54)