Real Estate (Key Information for Leases) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($) Tenant	Mar. 31, 2021 USD ($)	Sep. 30, 2021 USD ($) Tenant	Dec. 31, 2020 USD ($)
Lessor, Lease, Description [Line Items]
Weighted average remaining lease term			10 years 7 months 6 days
Leases classified as operating leases | Tenant	3,187		3,187
Leases classified as direct financing leases | Tenant	6		6
Rent deferral, year ending December 31, 2020				$ 52,019,000
Rent deferral, year ending December 31, 2021	$ 4,758,000		$ 4,758,000
Deferred rent repaid	6,068,000	$ 3,259,000	27,087,000
Deferred rent to be repaid during year ended December 31, 2021	$ 4,689,000		$ 4,689,000
Minimum
Lessor, Lease, Description [Line Items]
Initial lease term			10 years
Maximum
Lessor, Lease, Description [Line Items]
Initial lease term			20 years