Stock-Based Compensation Plans - Schedule of Stock Option Plan Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2015 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Available for Grant, Beginning balance	3,154,755
Shares Available for Grant, Authorized	6,494,292
Shares Available for Grant, Granted	(4,308,197)
Shares Available for Grant, Canceled	96,474
Shares Available for Grant, Ending balance	5,437,324
Number of Options, Beginning balance	5,970,382
Number of Options, Granted	4,308,197
Number of Options, Exercised	(293,250)
Number of Options, Canceled	(96,474)
Number of Options, Ending balance	9,888,855
Number Options, Options exercisable	4,536,982
Number of Options, Options vested and expected to vest	9,400,157
Weighted-Average Exercise Price, Beginning balance | $ / shares	$ 0.80
Weighted-Average Exercise Price, Granted | $ / shares	7.23
Weighted-Average Exercise Price, Exercised | $ / shares	0.61
Weighted-Average Exercise Price, Canceled | $ / shares	1.74
Weighted-Average Exercise Price, Ending balance | $ / shares	3.60
Weighted-Average Exercise Price, Options exercisable | $ / shares	1.23
Weighted-Average Exercise Price, Options vested and expected to vest | $ / shares	$ 3.53
Aggregate Intrinsic Value, Ending balance | $	$ 161,161
Aggregate Intrinsic Value, Options exercisable | $	82,455
Aggregate Intrinsic Value, Options vested and expected to vest | $	$ 153,714