Investments in Partially Owned Entities (Urban Edge Properties and PREIT Associates L.P.) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2017
Urban Edge Properties
Schedule Of Equity Method Investments
Ownership common shares, investee (in shares)	5,717,184		5,717,184
Equity method ownership percentage	4.80%		4.80%		5.40%
Closing share price (in dollars per share)	$ 23.73		$ 23.73
Equity Method Investment fair Value	$ 135,669		$ 135,669
Excess of investee's fair value over carrying amount	$ 93,777		$ 93,777
Average per unit carrying amount	$ 4.55		$ 4.55
Average issuance price per unit	$ 26.07		$ 26.07
Operating partnership units issued			14,000,000
Net gain resulting from operating partnership unit issuances	$ 15,900	$ 0	$ 15,900	$ 0
PREIT
Schedule Of Equity Method Investments
Ownership common shares, investee (in shares)	6,250,000		6,250,000
Equity method ownership percentage	8.00%		8.00%
Closing share price (in dollars per share)	$ 11.32		$ 11.32
Equity Method Investment fair Value	$ 70,750		$ 70,750
Excess of investee's carrying amount over fair value	46,854		46,854
Excess of investee's carrying amount over equity in net assets	$ 84,087		$ 84,087