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Transactions with Related Parties (Details) - Affiliated Entity - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Washington Housing Initiative
Related Party Transaction [Line Items]
Total capital commitments	$ 114,400,000		$ 114,400,000
Commitment	11,200,000		11,200,000
Remaining commitment	8,300,000		8,300,000
Supervisory Services of Properties \| BMS
Related Party Transaction [Line Items]
Related party transaction amount	4,900,000	$ 4,000,000.0	13,400,000	$ 12,600,000
Fees from Legacy JBG Funds and Washington Housing Initiative \| Legacy JBG Funds and Washington Housing Initiative
Related Party Transaction [Line Items]
Revenue from related parties	5,600,000	4,600,000	17,200,000	17,300,000
Receivables	3,500,000		3,500,000		$ 7,500,000
Office Rent \| Unconsolidated Real Estate Ventures
Related Party Transaction [Line Items]
Related party expenses	$ 246,000	$ 403,000	$ 1,000,000.0	$ 4,100,000