Investments - Activity in Real Estate Investments and Intangible Lease Liabilities Held for Sale (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($) Property	Jun. 30, 2020 USD ($) Property	Jun. 30, 2019 USD ($) Property
Number of Properties
Beginning balance | Property		1	0
Transfers to held for sale classification | Property		2	2
Sales | Property		(1)	0
Transfers to held and used classification | Property		0	0
Ending balance | Property	2	2	2
Real Estate Investments
Beginning balance		$ 1,211	$ 0
Transfers to held for sale classification	$ 3,765	1,792
Sales		(1,211)	0
Transfers to held and used classification		0	0
Ending balance	3,765	1,792	3,765
Intangible Lease Liabilities
Beginning balance		0	0
Transfers to held for sale classification		0	0
Sales		0	0
Transfers to held and used classification		0	0
Ending balance	0	0	0
Net Carrying Value
Beginning balance		1,211	0
Transfers to held for sale classification	3,765	1,792
Sales		(1,211)	0
Transfers to held and used classification		0	0
Ending balance	$ 3,765	$ 1,792	$ 3,765