Convertible Preferred Stock and Stockholders' Equity - Summary of Reserved Shares of Common Stock (Details) - shares	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Reserved shares of common stock	55,532,811	53,465,467
Stock Award Plans [Member]
Class of Stock [Line Items]
Reserved shares of common stock	3,216,028	4,438,503
Employee Stock Purchase Plan ("ESPP") [Member]
Class of Stock [Line Items]
Reserved shares of common stock	261,603	51,251
Series A Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Reserved shares of common stock	46,398,904	47,844,562
Series B Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Reserved shares of common stock	5,610,121
Warrants [Member]
Class of Stock [Line Items]
Reserved shares of common stock	46,155	1,131,151