Share Options - Stock Option Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2015
Number of options
Outstanding at beginning of period	7,426,159
Granted	2,718,127
Exercised	(2,512)
Forfeited and cancelled	(191,276)
Outstanding at end of period	9,950,498
Exercisable options	5,163,286
Vested and expected to vest	8,968,053
Weighted average exercise price
Outstanding at beginning of period	$ 3.98
Option exercise price per share	17.02
Exercised	7.36
Forfeited and cancelled	8.39
Outstanding at end of period	7.46
Exercisable options	2.86
Vested and expected to vest	$ 5.96
Aggregate intrinsic value
Outstanding at end of period	$ 144,651
Exercisable options	98,819
Vested and expected to vest	$ 143,856