Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Commitments and Contingencies [Line Items]
Number of properties with letters of credit | property	1
Aggregate proceeds, net	$ 44,656	$ 197,887	$ 896,456
Guarantees
Commitments and Contingencies [Line Items]
Amount of letters of credit outstanding	291
Circle East
Commitments and Contingencies [Line Items]
Redevelopment costs incurred	21,766
One Loudoun Downtown - Pads G & H
Commitments and Contingencies [Line Items]
Redevelopment costs incurred	14,711
Circle East, air rights
Commitments and Contingencies [Line Items]
Aggregate proceeds, net	11,820
Carillon
Commitments and Contingencies [Line Items]
Redevelopment costs incurred	5,358
Minimum | Circle East
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	42,000
Minimum | One Loudoun Downtown - Pads G & H
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	125,000
Minimum | Carillon
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	194,000
Maximum | Circle East
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	44,000
Maximum | One Loudoun Downtown - Pads G & H
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	135,000
Maximum | Carillon
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	$ 215,000