Dispositions and Assets Held for Sale - Narrative (Details) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	May 31, 2021 USD ($)	Apr. 30, 2021 USD ($) property	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of real estate venures in which cash was invested and land contributed | property		2
Gain (loss) on sale of real estate			$ 11,290		$ 11,290	$ 59,477
Income (loss) from unconsolidated real estate ventures, net			$ 3,953	$ (13,485)	$ 3,010	$ (16,177)
J.P. Morgan Global Alternatives ("J.P. Morgan") | Potomac Yard Mixed Use Development
Schedule of Equity Method Investments [Line Items]
Gain (loss) on sale of real estate		$ 11,300
Landmark and CBREI
Schedule of Equity Method Investments [Line Items]
Income (loss) from unconsolidated real estate ventures, net	$ 5,200