Real Estate (Narrative) (Details)				3 Months Ended
	May 05, 2021 USD ($) ft² ShoppingCenter	Feb. 24, 2021 USD ($)	Jul. 23, 2020 USD ($) Memberworkforce $ / ft²	Mar. 31, 2021 USD ($)
Real Estate Properties [Line Items]
Gain on sale of property				$ 1,047,000
Outparcel Building Adjacent to Kempsville Crossing [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Real Estate Properties [Line Items]
Proceeds from sale of outparcel building		$ 1,300,000
Outparcel Building Adjacent to Kempsville Crossing [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Operating Income [Member]
Real Estate Properties [Line Items]
Gain on sale of property		$ 1,000,000.0
Outparcel Building Adjacent to Kempsville Crossing [Member] | Subsequent Event [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Real Estate Properties [Line Items]
Proceeds from sale of outparcel building	$ 9,800,000
Commercial Lease Agreement [Member] | Development Asset [Member] | Government of the District of Columbia (“District”) [Member]
Real Estate Properties [Line Items]
Lease agreement entered date			Jul. 23, 2020
Number of member workforce planned to house new office headquarters | Memberworkforce			700
Term of lease			20 years 10 months
Initial annual net rent amount to be paid upon completion of building			$ 5,400,000
Annual escalator percentage to be paid on each anniversary of rent commencement			2.50%
Operating costs, property taxes and amortization of tenant improvements			$ 8,100,000
Annual net rent amount to be paid upon completion of building			$ 13,500,000
Free rent period			10 months
Tenant credit against either annual rent or any other tenant payment obligations including tenant improvement costs, in excess of tenant improvement allowance			$ 6,800,000
Amortized over period			240 months
Commercial Lease Agreement [Member] | Development Asset [Member] | Government of the District of Columbia (“District”) [Member] | Subsequent Event [Member]
Real Estate Properties [Line Items]
Area of commercial building | ft²	258,000
Area of commercial space leased percentage	100.00%
Number of redevelopment of existing shopping centers | ShoppingCenter	2
Initial term of construction loan	3 years
Percentage of interest in joint venture	10.00%
Commercial Lease Agreement [Member] | Development Asset [Member] | Government of the District of Columbia (“District”) [Member] | Subsequent Event [Member] | LIBOR Rate [Member]
Real Estate Properties [Line Items]
Construction loan initial interest	LIBOR plus 200 basis points
Basis spread on borrowings variable rate	200.00%
Commercial Lease Agreement [Member] | Development Asset [Member] | Government of the District of Columbia (“District”) [Member] | Subsequent Event [Member] | Office Space [Member]
Real Estate Properties [Line Items]
Area of commercial building | ft²	240,000
Commercial Lease Agreement [Member] | Development Asset [Member] | Government of the District of Columbia (“District”) [Member] | Subsequent Event [Member] | Street-Level Retail [Member]
Real Estate Properties [Line Items]
Area of commercial building | ft²	18,000
Commercial Lease Agreement [Member] | Development Asset [Member] | Government of the District of Columbia (“District”) [Member] | Between the 10th and 12th Lease Years [Member]
Real Estate Properties [Line Items]
Additional per rentable square foot tenant improvement allowance to be contributed | $ / ft²			9.38
Commercial Lease Agreement [Member] | Development Asset [Member] | Government of the District of Columbia (“District”) [Member] | Maximum [Member]
Real Estate Properties [Line Items]
Landlord contribution to be made per rentable square foot toward cost of tenant improvements | $ / ft²			155
Commercial Lease Agreement [Member] | Development Asset [Member] | Government of the District of Columbia (“District”) [Member] | Maximum [Member] | Subsequent Event [Member]
Real Estate Properties [Line Items]
Construction financing maximum amount	$ 105,000,000