Commitments and Contingencies (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2014 USD ($) ft² item	Dec. 31, 2016 USD ($) ft² lease item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Mar. 31, 2014 USD ($)	Jan. 31, 2013 USD ($)
Operating Leases
Leasehold improvements		$ 5,400,000
Future minimum lease payments
2017		6,914,000
2018		6,914,000
2019		6,413,000
2020		6,313,000
2021		6,313,000
2022 and thereafter		15,622,000
Total future minimum lease payment		48,489,000
Rent expense		$ 5,400,000	$ 2,700,000	$ 1,500,000
Corporate Headquarters Lease
Operating Leases
Office space (area) | ft²		88,000
Number of subleases | lease		2
Number of letters of credit | item		2
"First Space" Sublease
Operating Leases
Office space (area) | ft²		61,000
Restricted cash						$ 800,000
"Second Space" Sublease
Operating Leases
Office space (area) | ft²		27,000
Restricted cash					$ 300,000
Corporate Headquarters Sublease
Operating Leases
Office space (area) | ft²	48,000
Term of lease	84 months
Number of sublease phases | item	2
Sublease, First Phase
Operating Leases
Office space (area) | ft²	16,000
Monthly base rent	$ 60,730
Sublease, Second Phase
Operating Leases
Office space (area) | ft²	32,000
Monthly base rent	$ 121,460
Redwood City Lease
Operating Leases
Monthly base rent		$ 100,000
Security deposit		$ 100,000
Austin TX, Long-term Lease
Operating Leases
Office space (area) | ft²		94,000
Term of lease		132 months
Monthly base rent		$ 100,000
Maximum monthly base rent after escalation		200,000
Security deposit		400,000
Allowance for leasehold improvements		$ 7,800,000