Finance Receivables - Internal Credit Quality Rating (Details) $ in Thousands	Mar. 31, 2020 USD ($) tenant	Dec. 31, 2019 USD ($) tenant
Credit Quality Of Finance Receivables
Net investments in direct financing leases	$ 901,993	$ 944,286
Internally Assigned Grade1-3
Credit Quality Of Finance Receivables
Number of tenants | tenant	21	28
Net investments in direct financing leases	$ 652,628	$ 798,108
Internally Assigned Grade 4
Credit Quality Of Finance Receivables
Number of tenants | tenant	15	8
Net investments in direct financing leases	$ 249,365	$ 146,178
Internally Assigned Grade 5
Credit Quality Of Finance Receivables
Number of tenants | tenant	0	0
Net investments in direct financing leases	$ 0	$ 0