Real Estate - Summary of Property Dispositions (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2021 USD ($) ft²	Jun. 30, 2021 USD ($) ft²
Real Estate Properties [Line Items]
Gain on Sale/Reversal of Impairment	$ 48,857,000	$ 49,904,000
Discontinued Operations, Disposed of by Sale [Member]
Real Estate Properties [Line Items]
GLA | ft²	633,507	633,507
Sales Price		$ 100,723,500
Gain on Sale/Reversal of Impairment		$ 51,753,000
Discontinued Operations, Disposed of by Sale [Member] | Kempsville Crossing (Land Parcel) [Member]
Real Estate Properties [Line Items]
Location		Virginia Beach, VA
Date Sold		Feb. 24, 2021
Sales Price		$ 1,300,000
Gain on Sale/Reversal of Impairment		$ 1,047,000
Discontinued Operations, Disposed of by Sale [Member] | The Commons [Member]
Real Estate Properties [Line Items]
Location		Dubois, PA
GLA | ft²	203,309	203,309
Date Sold		May 05, 2021
Sales Price		$ 9,761,000
Gain on Sale/Reversal of Impairment		$ 1,849,000
Discontinued Operations, Disposed of by Sale [Member] | Camp Hill Shopping Center [Member]
Real Estate Properties [Line Items]
Location		Camp Hill, PA
GLA | ft²	430,198	430,198
Date Sold		Jun. 21, 2021
Sales Price		$ 89,662,500
Gain on Sale/Reversal of Impairment		$ 48,857,000