Commitments and Contingencies (Details)	1 Months Ended	9 Months Ended
	Feb. 28, 2021 property	Sep. 30, 2021 USD ($)	Jul. 23, 2021
Property Subject to or Available for Operating Lease [Line Items]
Debt, net		$ 1,830,589,000
Limited payment guarantee, percent of principle balance (up to)			25.00%
Winter Storm
Property Subject to or Available for Operating Lease [Line Items]
Number of properties damaged | property	1
Write-off of fixed assets		1,200,000
Restoration liability		7,200,000
Business interruption costs		3,900,000
Insurance proceeds		13,000,000
Winter Storm | Other Income
Property Subject to or Available for Operating Lease [Line Items]
Insurance proceeds		700,000
Winter Storm | Accounts Payable and Accrued Liabilities
Property Subject to or Available for Operating Lease [Line Items]
Restoration liability		2,000,000
One and Two Commerce Square | Preferred Equity Investment
Property Subject to or Available for Operating Lease [Line Items]
Other commitments		20,000,000
Amount committed to date		2,100,000
Drexel Square
Property Subject to or Available for Operating Lease [Line Items]
Other commitments		7,600,000
Estimated potential additional contribution obligation		2,400,000
4040 Wilson Venture
Property Subject to or Available for Operating Lease [Line Items]
Debt, net		150,000,000
Guarantees, maximum exposure amount (up to)		41,300,000
Unconsolidated Real Estate Ventures
Property Subject to or Available for Operating Lease [Line Items]
Real estate ventures aggregate indebtedness		$ 958,800,000