Stockholders' Equity (Deficit) - Stock-Based Compensation (Details) - shares	1 Months Ended	6 Months Ended
	Dec. 31, 2015	Jun. 30, 2016
2015 Equity Incentive Plan
Stock-based compensation
Expiration period	10 years
Total shares that may be issued		17,251,115
Additional shares authorized		8,000,000
Shares available for grant		5,429,635
Automatic annual increase in shares authorized, percent of common stock outstanding		3.50%
2015 Equity Incentive Plan | Maximum
Stock-based compensation
Shares available for grant		9,251,115
1997 Stock Option Plan
Stock-based compensation
Expiration period		10 years