Common Stock (Details)
11 Months Ended 12 Months Ended
Dec. 31, 2014
shares
Dec. 31, 2016
USD ($)
Vote
shares
Dec. 31, 2015
shares
Common Stock      
Common stock, shares authorized for issuance   290,000,000 20,000,000
Preferred stock, shares authorized for issuance   10,000,000 0
Number of votes per share of common stock | Vote   1  
Dividends on common stock | $   $ 0  
Shares of common stock reserved for issuance, on an as-converted basis      
Convertible preferred stock, shares authorized 8,921,438 0 14,274,741
Shares available for future option grants 837,547 2,475,600 2,559,499
Outstanding options 32,320 2,350,582 784,136
Unvested restricted common stock (founders and early exercise of stock options) 768,706 611,698 924,535
Shares reserved for employee stock purchase plan   200,000  
Total 10,560,011 5,637,880 18,542,911
Common Stock      
Common Stock      
Shares of common stock sold to founders 1,046,749   384,866