Share Capital - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended			29 Months Ended
	Dec. 31, 2018	Jan. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 30, 2018
Share Capital [Line Items]
Number of warrants cashless exercised			504,225	1,418,711
Warrants exercise price	$ 3.59		$ 3.59	$ 3.59		$ 3.59
Credit facility repayment date			Dec. 31, 2013
Class of Warrant or Right, Date from which Warrants or Rights Exercisable			Jan. 31, 2016
Unrecognized compensation cost	$ 43,315		$ 43,315			$ 43,315
Unrecognized compensation cost expected recognition weighted average period			2 years 7 months 6 days
Weighted average grant date exercise price of options granted			$ 23.73	10.53	$ 7.37
Weighted average grant date fair values options forfeited and cancelled			$ 15.09	$ 12.54	$ 9.72
Aggregate intrinsic values options exercised			$ 57,813	$ 17,945	$ 7,637
Fair value of ordinary shares	$ 33.48		$ 33.48	$ 20.20	$ 7.85	$ 33.48
ESPP
Share Capital [Line Items]
Ordinary shares available for grant	3,122,410		3,122,410			3,122,410
Percentage of increase in shares outstanding			1.00%
Option
Share Capital [Line Items]
Stock awards granted, vesting period			4 years
Stock awards granted, expiration period			10 years
RSUs
Share Capital [Line Items]
Stock awards granted, vesting period			3 years
2015 Plan
Share Capital [Line Items]
Percentage increase in number of shares available for issuance	4.00%
Number of shares available for issuance	27,035,515		27,035,515			27,035,515	23,307,208
Ordinary shares available for grant	13,843,105		13,843,105			13,843,105
2015 Plan | Option
Share Capital [Line Items]
Stock awards granted, vesting period			4 years
Stock awards granted, expiration period			10 years
2015 Plan | RSUs
Share Capital [Line Items]
Stock awards granted, vesting period			3 years
Series H Convertible Preferred Shares
Share Capital [Line Items]
Warrants exercise price	$ 18.77		$ 18.77			$ 18.77
Warrants issued to purchase of preferred shares			975,644
Warrant
Share Capital [Line Items]
The Number of ordinary shares that originally could be purchased by exercise of warrants in cash			3,879	6,498
Warrants exercised to ordinary shares		315,155
Warrant | Warrants Not Settleable in Cash
Share Capital [Line Items]
Number of shares issued upon the exercise of warrants			437,081	803,138
Ordinary Shares
Share Capital [Line Items]
Number of shares issued upon the exercise of warrants			87,372
Issuance of shares in connection with employee stock purchase plan(in shares)				167,433	92,388
Ordinary Shares | ESPP
Share Capital [Line Items]
Issuance of shares in connection with employee stock purchase plan(in shares)						347,193