Qualified Affordable Housing Project Investments, Total Capital Commitments

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Transactions with Vornado and Related Parties (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Qualified Affordable Housing Project Investments, Total Capital Commitments	$ 78,000,000.0		$ 78,000,000.0
Third-party real estate services, including reimbursements	29,487,000	$ 24,160,000	57,178,000	$ 48,490,000
Corporate and other	11,559,000	8,603,000	23,873,000	17,017,000
Affiliated Entity [Member] \| Washington Housing Initiative [Member]
Related Party Transaction [Line Items]
Qualified Affordable Housing Project Investments, Commitment	7,600,000		7,600,000
Affiliated Entity [Member] \| Legacy JBG Funds [Member]
Related Party Transaction [Line Items]
Corporate and other	1,300,000	1,200,000	2,600,000	2,400,000
Affiliated Entity [Member] \| Separation and Combination transaction \| Vornado Realty Trust [Member]
Related Party Transaction [Line Items]
Expenses from related parties		1,100,000		2,300,000
Revenue from related parties	489,000	444,000	977,000	1,000,000.0
Affiliated Entity [Member] \| Supervisory Services of Properties [Member] \| BMS
Related Party Transaction [Line Items]
Related party transaction amount	5,400,000	6,100,000	10,600,000	10,100,000
Affiliated Entity [Member] \| Fees from Legacy JBG Funds and Washington Housing Initiative [Member] \| Legacy JBG Funds and Washington Housing Initiative [Member]
Related Party Transaction [Line Items]
Third-party real estate services, including reimbursements	10,000,000.0		18,400,000
Accounts Receivable, Related Parties	$ 5,800,000		$ 5,800,000
Affiliated Entity [Member] \| Fees from Legacy JBG Funds \| Legacy JBG Funds [Member]
Related Party Transaction [Line Items]
Third-party real estate services, including reimbursements		$ 8,300,000		$ 16,900,000
Accounts Receivable, Related Parties					$ 3,600,000