Finance Receivables - Internal Credit Quality Rating (Details) $ in Thousands	Jun. 30, 2021 USD ($) tenant	Dec. 31, 2020 USD ($) tenant
Credit Quality Of Finance Receivables
Net investments in direct financing leases	$ 704,921	$ 765,784
Internally Assigned Grade1-3
Credit Quality Of Finance Receivables
Number of tenants (tenant) | tenant	18	18
Net investments in direct financing leases	$ 536,724	$ 587,103
Internally Assigned Grade 4
Credit Quality Of Finance Receivables
Number of tenants (tenant) | tenant	10	9
Net investments in direct financing leases	$ 168,197	$ 141,944
Internally Assigned Grade 5
Credit Quality Of Finance Receivables
Number of tenants (tenant) | tenant	0	2
Net investments in direct financing leases	$ 0	$ 36,737