Finance Receivables - Internal Credit Quality Rating (Details) $ in Thousands	Jun. 30, 2020 USD ($) tenant	Dec. 31, 2019 USD ($) tenant
Credit Quality Of Finance Receivables
Net investments in direct financing leases	$ 800,184	$ 944,286
Internally Assigned Grade1-3
Credit Quality Of Finance Receivables
Number of tenants | tenant	19	28
Net investments in direct financing leases	$ 605,740	$ 798,108
Internally Assigned Grade 4
Credit Quality Of Finance Receivables
Number of tenants | tenant	11	8
Net investments in direct financing leases	$ 157,707	$ 146,178
Internally Assigned Grade 5
Credit Quality Of Finance Receivables
Number of tenants | tenant	2	0
Net investments in direct financing leases	$ 36,737	$ 0