Net Loss per Share - Anti-Dilutive Securities (Details) - shares
11 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2016
Dec. 31, 2015
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect      
Shares of common stock equivalents 4,196,494 2,962,280 15,983,412
Convertible Preferred Stock.      
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect      
Shares of common stock equivalents 3,395,468   14,274,741
Common stock subject to repurchase      
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect      
Shares of common stock equivalents 768,706 611,698 924,535
Outstanding options      
Excluded from the calculation of diluted net loss per share, due to anti-dilutive effect      
Shares of common stock equivalents 32,320 2,350,582 784,136