Mortgage Loans Payable And Unsecured Credit Facilities (Schedule Of Mortgage Loans Payable Repaid) (Details) - Mortgage Loans Payable [Member] - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Gold Star Plaza [Member]
Debt Instrument [Line Items]
Repayment date	Mar. 10, 2016
Principal payoff amount	$ 953,000
West Bridgewater [Member]
Debt Instrument [Line Items]
Repayment date	Jun. 06, 2016
Principal payoff amount	$ 10,037,000
Hamburg Square [Member]
Debt Instrument [Line Items]
Repayment date	Jul. 01, 2016
Principal payoff amount	$ 4,569,000
Meadows Marketplace [Member]
Debt Instrument [Line Items]
Repayment date	Aug. 01, 2016
Principal payoff amount	$ 9,089,000
Carman's Plaza [Member]
Debt Instrument [Line Items]
Repayment date	Aug. 01, 2016
Principal payoff amount	$ 33,500,000
San Souci Plaza [Member]
Debt Instrument [Line Items]
Repayment date	Sep. 01, 2016
Principal payoff amount	$ 27,200,000
Camp Hill [Member]
Debt Instrument [Line Items]
Repayment date	Sep. 30, 2016
Principal payoff amount	$ 60,742,000
Swede Square [Member]
Debt Instrument [Line Items]
Repayment date	Dec. 29, 2016
Principal payoff amount	$ 9,652,000
Golden Triangle [Member]
Debt Instrument [Line Items]
Repayment date	Dec. 30, 2016
Principal payoff amount	$ 18,496,000
New London Mall [Member]
Debt Instrument [Line Items]
Repayment date		Feb. 01, 2015
Principal payoff amount		$ 27,365,000
Oak Ridge Shopping Center [Member]
Debt Instrument [Line Items]
Repayment date		Mar. 11, 2015
Principal payoff amount		$ 3,155,000
Pine Grove Plaza [Member]
Debt Instrument [Line Items]
Repayment date		Jun. 01, 2015
Principal payoff amount		$ 5,139,000
Quartermaster Plaza [Member]
Debt Instrument [Line Items]
Repayment date		Jul. 01, 2015
Principal payoff amount		$ 41,327,000
Groton Shopping Center [Member]
Debt Instrument [Line Items]
Repayment date		Jul. 01, 2015
Principal payoff amount		$ 10,953,000
Jordan Lane [Member]
Debt Instrument [Line Items]
Repayment date		Aug. 02, 2015
Principal payoff amount		$ 11,682,000
Southington Center [Member]
Debt Instrument [Line Items]
Repayment date		Aug. 02, 2015
Principal payoff amount		$ 5,129,000
Oakland Mills [Member]
Debt Instrument [Line Items]
Repayment date		Sep. 01, 2015
Principal payoff amount		$ 4,385,000