Acquisitions and Developments in Progress - Variable Interest Entities (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
One Loudoun Downtown - Pads G & H
Variable Interest Entity [Line Items]
Development costs funded by the Company through a loan to the joint venture	$ 758
Carillon
Variable Interest Entity [Line Items]
Noncontrolling interest balance	2,217
Multi-family | RPAI | One Loudoun Downtown - Pads G & H
Variable Interest Entity [Line Items]
Noncontrolling interest, ownership percentage by parent		90.00%
Multi-family | RPAI | Carillon
Variable Interest Entity [Line Items]
Noncontrolling interest, ownership percentage by parent		95.00%
Medical office building | RPAI | Carillon
Variable Interest Entity [Line Items]
Noncontrolling interest, ownership percentage by parent		95.00%
Net investment properties
Variable Interest Entity [Line Items]
Development costs incurred	59,678		$ 12,445
Net investment properties | One Loudoun Downtown - Pads G & H
Variable Interest Entity [Line Items]
Development costs incurred	59,678		8,830
Net investment properties | Multi-family | Carillon
Variable Interest Entity [Line Items]
Development costs incurred	0		2,940
Net investment properties | Medical office building | Carillon
Variable Interest Entity [Line Items]
Development costs incurred	0		675
Other assets, net
Variable Interest Entity [Line Items]
Development costs incurred	336		164
Other assets, net | One Loudoun Downtown - Pads G & H
Variable Interest Entity [Line Items]
Development costs incurred	336		164
Other assets, net | Multi-family | Carillon
Variable Interest Entity [Line Items]
Development costs incurred	0		0
Other assets, net | Medical office building | Carillon
Variable Interest Entity [Line Items]
Development costs incurred	0		0
Other liabilities
Variable Interest Entity [Line Items]
Development costs incurred	7,361		1,707
Other liabilities | One Loudoun Downtown - Pads G & H
Variable Interest Entity [Line Items]
Development costs incurred	7,361		1,546
Other liabilities | Multi-family | Carillon
Variable Interest Entity [Line Items]
Development costs incurred	0		32
Other liabilities | Medical office building | Carillon
Variable Interest Entity [Line Items]
Development costs incurred	0		129
Noncontrolling interests
Variable Interest Entity [Line Items]
Development costs incurred	4,507		3,596
Noncontrolling interests | One Loudoun Downtown - Pads G & H
Variable Interest Entity [Line Items]
Development costs incurred	4,507		1,869
Noncontrolling interests | Multi-family | Carillon
Variable Interest Entity [Line Items]
Development costs incurred	0		1,454
Noncontrolling interests | Medical office building | Carillon
Variable Interest Entity [Line Items]
Development costs incurred	$ 0		$ 273