Summary Of Significant Accounting Policies (Narrative) (Details)		12 Months Ended
	Jan. 23, 2015	Dec. 31, 2016 USD ($) Segment shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense		$ 37,100,000	$ 35,000,000	$ 35,000,000
Cash at consolidated joint ventures		500,000	200,000
Allowance for doubtful accounts receivable		4,700,000	4,400,000
Provision for doubtful accounts included in operating, maintenance and management expenses		$ 1,200,000	$ 1,400,000	$ 1,900,000
Number of reportable segment | Segment		1
Remaining contractual payment for ground lease and executive office lease agreements		$ 17,100,000
Ground lease and executive office lease agreements remaining weighted average term		46 years 1 month 6 days
2012 Stock Incentive Plan [Member]
Summary Of Significant Accounting Policies [Line Items]
Maximum number of shares may be issued under the plan | shares		4,500,000
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]
Summary Of Significant Accounting Policies [Line Items]
Acquired ownership percentage in joint venture	60.00%
Percentage of joint venture ownership	100.00%
New London Mall [Member] | New London Joint Venture [Member]
Summary Of Significant Accounting Policies [Line Items]
Acquired ownership percentage in joint venture	60.00%
Variable Interest Entity, Primary Beneficiary [Member] | Other Ownership Interest [Member]
Summary Of Significant Accounting Policies [Line Items]
VIE real estate owned carrying value		$ 39,200,000
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		$ 26,200,000
VIE mortgage payable		$ 0