Commitments and Contingencies (Summary of Reconciliation of Undiscounted Future Minimum Lease Payments for its Ground Lease and Executive Office Lease Agreements to Right-of-Use Liabilities) (Details)	Dec. 31, 2019 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2020	$ 1,095,000
2021	956,000
2022	955,000
2023	956,000
2024	956,000
Thereafter	29,511,000
Total undiscounted future minimum lease payments	34,429,000
Future minimum lease payments, discount	(20,651,000)
Right-of-use liabilities	$ 13,778,000