Commitments and Contingencies (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) ft²	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) ft² item	Sep. 30, 2017 USD ($)
Agreements for Office Space
Area leased from third party | ft²	33,019		33,019
Rent expense under operating leases	$ 204	$ 110	$ 682	$ 284
Contractual Obligation, Fiscal Year Maturity [Abstract]
2018	312		312
2019	1,100		1,100
2020	1,037		1,037
2021	1,054		1,054
2022	791		791
Thereafter	531		531
Total	$ 4,825		$ 4,825
Number of capital lease arrangements | item			2
Capital lease term			4 years