Investments in Partially Owned Entities (Urban Edge Properties and PREIT) (Details) $ / shares in Units, $ in Thousands	Mar. 31, 2018 USD ($) $ / shares shares
UE
Schedule Of Equity Method Investments
Equity method ownership percentage	4.50%
Closing share price (in dollars per share) | $ / shares	$ 21.35
Equity method investment fair value	$ 122,062
Excess of investee's fair value over carrying amount	$ 77,886
PREIT
Schedule Of Equity Method Investments
Ownership common shares, investee (in shares) | shares	6,250,000
Equity method ownership percentage	8.00%
Closing share price (in dollars per share) | $ / shares	$ 9.65
Equity method investment fair value	$ 60,313
Excess of investee's fair value over carrying amount	4,874
Excess of investee's carrying amount over equity in net assets	$ 33,976
Partnership Interest | UE
Schedule Of Equity Method Investments
Ownership common shares, investee (in shares) | shares	5,717,184