Stockholders' Equity - Schedule of Reserved Shares of Common Stock (Details) - shares	Sep. 30, 2017	Dec. 31, 2016
Stock-based compensation
Reserved shares of common stock	17,717,592	15,535,656
Stock options
Stock-based compensation
Reserved shares of common stock	7,635,846	10,048,607
RSUs
Stock-based compensation
Reserved shares of common stock	524,765	323,663
Shares available for future grant
Stock-based compensation
Reserved shares of common stock	9,556,981	5,163,386