Real Estate - Schedule of Construction in Progress (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Real Estate [Line Items]
Construction in progress	$ 191,707	$ 69,477
Twinbrook Quarter
Real Estate [Line Items]
Construction in progress	127,348	0
Hampden House
Real Estate [Line Items]
Construction in progress	53,619	50,723
The Waycroft
Real Estate [Line Items]
Construction in progress	0	8,651
Ashbrook Marketplace
Real Estate [Line Items]
Construction in progress	0	153
Other
Real Estate [Line Items]
Construction in progress	$ 10,740	$ 9,950