Summary Of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense	$ 36,100,000	$ 36,500,000	$ 37,100,000
Cash at consolidated joint ventures	200,000	300,000
Allowance for doubtful accounts receivable	5,900,000	4,700,000
Provision for doubtful accounts included in operating, maintenance and management expenses	$ 2,200,000	$ 1,700,000	$ 1,200,000
Number of reportable segment | Segment	1
Capitalized leasing costs	$ 2,800,000
Operating lease, right-of-use asset	15,000,000
Operating lease, liability	$ 15,000,000
2017 Stock Incentive Plan [Member]
Summary Of Significant Accounting Policies [Line Items]
Maximum number of shares may be issued under the plan | shares		4,000,000
Maximum number of shares to be granted per year to a participant | shares		500,000
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Real estate investments useful life	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Real estate investments useful life	40 years
New London Mall [Member] | New London Joint Venture [Member]
Summary Of Significant Accounting Policies [Line Items]
Acquired ownership percentage in joint venture				60.00%
Percentage of joint venture ownership				100.00%
Variable Interest Entity, Primary Beneficiary [Member] | Other Ownership Interest [Member]
Summary Of Significant Accounting Policies [Line Items]
VIE real estate owned carrying value	$ 38,100,000
VIE mortgage payable	$ 0
Variable Interest Entity, Primary Beneficiary [Member] | Crossroads II [Member] | Other Ownership Interest [Member]
Summary Of Significant Accounting Policies [Line Items]
Ownership percentage	60.00%
Variable Interest Entity, Primary Beneficiary [Member] | San Souci Plaza [Member]
Summary Of Significant Accounting Policies [Line Items]
VIE real estate owned carrying value	$ 26,900,000
VIE mortgage payable	$ 0