Stockholders' Equity - Schedule of Reserve Share of Common Stock for Issuance (Details) - shares	Dec. 31, 2016	Dec. 31, 2015	Jul. 31, 2015
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	30,595,000	27,307,000
Twenty Fifteen Equity Incentive Plan
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	11,081,000	12,006,000	11,400,000
Twenty Fifteen Employee Stock Purchase Plan
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	2,511,000	1,000,000
Employee Stock Option
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	12,897,000	12,795,000
Restricted Stock Units (RSUs)
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	4,106,000	1,506,000