Common Stock and Stockholders' Equity - Stock Plan and Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Stock-based Awards
Vesting period (in years)	4 years
Stock options
Shares Available for Grant
Balance, beginning of period (in shares)	343,216
Increase in Plan authorized shares	2,876,722
Stock options grants (in shares)	(2,835,709)
Stock options forfeited (in shares)	361,643
Balance, end of period (in shares)	745,872		343,216
Number of Shares Outstanding
Balance, beginning of period (in shares)	6,839,868
Stock option grants (in shares)	2,835,709
Stock option exercised (in shares)	(131,468)
Stock options forfeited (in shares)	(361,643)
Balance, end of period (in shares)	9,182,466		6,839,868
Vested or expected to vest at end of period (in shares)	9,182,466
Exercisable as of end of period (in shares)	2,044,937
Weighted-Average Exercise Price
Balance, beginning of period (in dollars per share)	$ 11.70
Stock option grants (in dollars per share)	22.14
Stock option exercised (in dollars per share)	8.84
Stock options forfeited (in dollars per share)	15.87
Balance, end of period (in dollars per share)	14.80		$ 11.70
Vested or expected to vest at end of period (in dollars per share)	14.80
Exercisable as of end of period (in dollars per share)	$ 7.50
Weighted-average remaining contractual life in Years
Weighted-average remaining contractual life (in years)	8 years 9 months 26 days		8 years 7 months 21 days
Vested or expected to vest at end of period (in years)	8 years 9 months 26 days
Exercisable as of end of period (in years)	7 years 2 months 23 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 93,634		$ 36,795
Stock options exercised	1,630
Stock options forfeited	1,823
Vested or expected to vest at end of period	93,634
Exercisable as of end of period	35,794
Grant-date fair value of stock options granted during the period	$ 29,900
Fair value assumptions
Volatility, minimum (as a percent)	46.70%	44.70%
Volatility, maximum (as a percent)	47.70%	46.00%
Expected life (in years)	6 years 1 month 6 days	6 years
Risk-free interest rate, minimum	2.10%	1.24%
Risk-free interest rate, maximum	2.30%	1.91%
Dividend yield (as a percent)	0.00%	0.00%
Weighted-average fair value of underlying common stock	$ 10.54	$ 5.71
Stock options | Maximum
Stock-based Awards
Exercisable period (in years)	10 years