SCHEDULE III REAL ESTATE AND ACCUMULATED DEPRECIATION - Reconciliation of Carrying Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Initial Cost to Company
Land	$ 44,060
Buildings and Improvements	272,927
Costs Capitalized Subsequent to Acquisition, Net	112,792
Impairment/Write Downs	(17,892)
Cost Amount Carried at Close of Period
Land	44,060
Buildings and Improvements	367,827
Total	411,887
Accumulated Depreciation	180,535	$ 169,530	$ 156,439	$ 143,319
1225 Seventeenth Street
Initial Cost to Company
Land	22,400
Buildings and Improvements	110,090
Costs Capitalized Subsequent to Acquisition, Net	48,374
Impairment/Write Downs	(4,877)
Cost Amount Carried at Close of Period
Land	22,400
Buildings and Improvements	153,587
Total	175,987
Accumulated Depreciation	65,171
1250 H Street, NW
Initial Cost to Company
Land	5,975
Buildings and Improvements	53,778
Costs Capitalized Subsequent to Acquisition, Net	22,316
Impairment/Write Downs	(6,046)
Cost Amount Carried at Close of Period
Land	5,975
Buildings and Improvements	70,048
Total	76,023
Accumulated Depreciation	41,761
206 East 9th Street
Initial Cost to Company
Land	7,900
Buildings and Improvements	38,533
Costs Capitalized Subsequent to Acquisition, Net	9,952
Impairment/Write Downs	(1,710)
Cost Amount Carried at Close of Period
Land	7,900
Buildings and Improvements	46,775
Total	54,675
Accumulated Depreciation	14,003
Bridgepoint Square
Initial Cost to Company
Land	7,785
Buildings and Improvements	70,526
Costs Capitalized Subsequent to Acquisition, Net	32,150
Impairment/Write Downs	(5,259)
Cost Amount Carried at Close of Period
Land	7,785
Buildings and Improvements	97,417
Total	105,202
Accumulated Depreciation	$ 59,600