Annual report pursuant to Section 13 and 15(d)

Income Taxes - Reconciliation - (Details)

v3.8.0.1
Income Taxes - Reconciliation - (Details)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Reconciliation of statutory income tax rate to effective tax rate:      
Federal income tax computed at federal statutory tax rate (as a percent) 34.00% 34.00% 34.00%
State income tax, net of federal benefit (as a percent) 5.35% 4.79% 4.70%
Permanent items (as a percent) (1.57%) (2.83%) (3.33%)
Federal and state research and development credits (as a percent) 7.36% 2.93% 2.66%
Rate change (as a percent) (31.79%)    
Other (as a percent) 0.66% (0.08%) 0.12%
Change in valuation allowance (as a percent) (14.02%) (38.81%) (38.15%)
Effective tax rate (as a percent) (0.01%) 0.00% 0.00%