Stockholders' Equity - Schedule of Reserve Share of Common Stock for Issuance (Details) - shares	Dec. 31, 2015	Jul. 31, 2015	Dec. 31, 2014
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	27,307,000		67,890,000
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Shares of common stock reserved for issuance			12,007,000
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Shares of common stock reserved for issuance			10,758,000
Series C Convertible Preferred Stock
Class Of Stock [Line Items]
Shares of common stock reserved for issuance			13,613,000
Series D Convertible Preferred Stock
Class Of Stock [Line Items]
Shares of common stock reserved for issuance			7,584,000
Series E Convertible Preferred Stock
Class Of Stock [Line Items]
Shares of common stock reserved for issuance			10,879,000
Twenty Fifteen Equity Incentive Plan
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	12,006,000	11,400,000
Twenty Thirteen Equity Incentive Plan
Class Of Stock [Line Items]
Shares of common stock reserved for issuance			694,000
Twenty Fifteen Employee Stock Purchase Plan
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	1,000,000
Employee Stock Option
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	12,795,000		11,408,000
Restricted Stock Units (RSUs)
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	1,506,000		947,000