Variable Interest Entities (Narrative) (Details) $ in Thousands		6 Months Ended		12 Months Ended
		Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($) joint_venture property	Dec. 31, 2016 USD ($) joint_venture property
Variable Interest Entity [Line Items]
Number of VIE real estate joint ventures guaranteed by company | joint_venture			1	1
Acquired property net book value	[1]		$ 212,692	$ 476,117
Consolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Number of VIE real estate joint ventures | joint_venture			9	9
Number of neighborhood/community shopping centers | property			22	25
Acquired property net book value				$ 249,500
Variable interest entity, consolidated, additional contributions made			$ 100	$ 2,500
Unconsolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Number of VIE real estate joint ventures | joint_venture			2	2
Investment in real estate joint ventures and partnerships, net			$ 28,758	$ 886
Variable interest entity, nonconsolidated, additional future funding			101,000
Scenario, Forecast [Member] | Consolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Variable interest entity, consolidated, additional contributions made		$ 100
Other Liabilities [Member] | Unconsolidated Variable Interest Entities [Member]
Variable Interest Entity [Line Items]
Investment in real estate joint ventures and partnerships, net			$ (7,000)	$ (9,000)

[1] Consolidated variable interest entities' assets held as collateral and debt included in the above balances at March 31, 2017 and December 31, 2016 are Property, net of $216,223 and $476,117; Accrued Rent and Accounts Receivable, net of $9,723 and $11,066; Cash and Cash Equivalents of $7,797 and $9,560; Debt, net of $46,902 and $47,112.