Commitments and Contingencies (Details)	1 Months Ended			3 Months Ended		9 Months Ended
	Nov. 30, 2016 USD ($)	Oct. 31, 2016 ft²	Oct. 31, 2015 USD ($)	Sep. 30, 2017 USD ($) ft²	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) ft² lease item	Sep. 30, 2016 USD ($)
Future minimum lease payments
2017 (remaining 3 months)				$ 1,842,000		$ 1,842,000
2018				8,035,000		8,035,000
2019				8,548,000		8,548,000
2020				8,675,000		8,675,000
2021				8,913,000		8,913,000
2022 and thereafter				23,897,000		23,897,000
Total future minimum lease payment				59,910,000		59,910,000
Rent expense				$ 1,700,000	$ 1,300,000	$ 5,100,000	$ 3,900,000
Corporate Headquarters Lease
Operating Leases
Office space (area) | ft²				104,000		104,000
Security Deposit	$ 100,000			$ 700,000		$ 700,000
Term of lease						84 months
Security deposit	100,000			$ 700,000		$ 700,000
Number of office space locations | item						2
"First Space" Sublease
Operating Leases
Office space (area) | ft²				88,000		88,000
Monthly base rent						$ 309,372
"Second Space" Sublease
Operating Leases
Office space (area) | ft²				16,000		16,000
Monthly base rent						$ 60,730
Corporate Headquarters Sublease
Operating Leases
Office space (area) | ft²		13,000
Monthly base rent	$ 49,140
Term of lease		28 months
Percentage of annual increase in monthly base rent	3.00%
Austin TX, Long-term Lease
Operating Leases
Office space (area) | ft²				94,000		94,000
Monthly base rent						$ 100,000
Security Deposit				$ 400,000		$ 400,000
Term of lease						132 months
Maximum monthly base rent after escalation						$ 200,000
Security deposit				400,000		400,000
Allowance for leasehold improvements				$ 7,800,000		$ 7,800,000
Austin TX, Short-term Lease
Operating Leases
Monthly base rent			$ 12,900
Security Deposit			$ 12,900
Term of lease			1 year
Security deposit			$ 12,900
First space sublease terminated
Operating Leases
Number of subleases | lease						2
Number of lessors | item						2
First space sublease terminated, phase one
Operating Leases
Office space (area) | ft²				61,000		61,000
Restricted cash				$ 800,000		$ 800,000
First space sublease terminated, phase two
Operating Leases
Office space (area) | ft²				27,000		27,000
Restricted cash				$ 300,000		$ 300,000