Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) office option	Jun. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Number of leased corporate offices | office			2
Finance lease cost	$ 12	$ 13	$ 24	$ 26
New York
Lessee, Lease, Description [Line Items]
Lessee, operating lease, renewal term	5 years		5 years
Michigan
Lessee, Lease, Description [Line Items]
Lessee, operating lease, number of options | option			2
Lessee, operating lease, renewal term	5 years		5 years
Non-recoverable operating expense
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 290	290	$ 581	581
General and administrative expense
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 143	$ 251	$ 291	$ 484