Commitments and Contingencies - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) lease	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Oct. 01, 2019 USD ($)	Jan. 01, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Non-cash lease expense	$ 301	$ 49	$ 647	$ 101
Operating lease - right of use asset, net	1,806		1,806		$ 3,117
Operating lease liability	1,961		$ 1,961
Number of leases exited | lease			2
Disposal of ROU assets and operating lease liability			$ 214
ROU disposal	317		317
Lease liability disposal	333		333
Revenue	2,816	$ 2,439	$ 8,144	$ 5,033
New York
Lessee, Lease, Description [Line Items]
Number of leases exited | lease			1
London
Lessee, Lease, Description [Line Items]
Number of leases exited | lease			1
Professional and other services | Major customer
Lessee, Lease, Description [Line Items]
Revenue	$ 200		$ 800
Percentage of revenue	7.00%		10.00%
Revenue
Lessee, Lease, Description [Line Items]
Percentage of revenue	100.00%	100.00%	100.00%	100.00%
Calculation error | Adjustment
Lessee, Lease, Description [Line Items]
Operating lease - right of use asset, net	$ 195		$ 195
Operating lease liability	$ 195		$ 195
Accounting standards update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease - right of use asset, net						$ 3,376	$ 99
Operating lease liability						$ 3,578	$ 111
Incremental borrowing rate						6.00%	7.75%
Minimum
Lessee, Lease, Description [Line Items]
Term of contract	1 year		1 year
Renewal term	12 months		12 months
Maximum
Lessee, Lease, Description [Line Items]
Term of contract	4 years		4 years
Renewal term	5 years		5 years