Basis of Presentation and Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) Segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Minimum percentage of taxable income distributed to shareholders	90.00%
Income tax expense	$ 3,265,000	$ 3,643,000	$ 1,493,000
Number of reportable segments | Segment	2
Accounting Standards Update [Extensible Enumeration]	us-gaap:AccountingStandardsUpdate202006Member
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2022
Change in accounting principle, accounting standards update, immaterial effect [true false]	true
111 Sutter Street [Member]
Proportionate share of real estate impairment loss	$ 31,685,000
Taxable REIT Subsidiaries [Member]
Income tax expense	1,942,000	2,024,000	698,000
Deferred income tax expense (benefit)	$ 101,000	$ 703,000	$ 32,000
Minimum [Member]
Estimated useful lives of the assets, years	5
Lease term	5 years
Maximum [Member]
Estimated useful lives of the assets, years	40 years
Lease term	15 years