Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands, ft² in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) ft² number_of_retirement_plan segment foreign	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Significant Accounting Policies [Line Items]
Square footage of operating properties (in square feet) | ft²	32.5
Real estate asset, estimated useful life	40 years
Single purpose entity, ownership percentage	100.00%
Vesting period (years) for share options and awards	3 years
Number of foreign operations | foreign	0
Number of reportable segments | segment	1
Accumulated other comprehensive loss	$ 1,876,160	$ 1,750,699	$ 1,809,842	$ 1,716,896
Rentals, net	472,446	517,836	563,183
Other	14,179	13,311	9,980
Interest Rate Contracts [Member] | Cash Flow Hedging [Member]
Significant Accounting Policies [Line Items]
Cash flow hedge gain (loss) to be amortized within 12 months	900
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Significant Accounting Policies [Line Items]
Accumulated other comprehensive loss	$ 3,614	4,501	7,424	$ 6,403
Accounting Standards Update 2016-02 [Member]
Significant Accounting Policies [Line Items]
Rentals, net		1,300	2,500
Other		$ (1,300)	$ (2,500)
Supplemental Employee Retirement Plan [Member]
Significant Accounting Policies [Line Items]
Number of retirement plans | number_of_retirement_plan	2
Supplemental Employee Retirement Plan [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Defined contribution plan, vesting period	5 years
Supplemental Employee Retirement Plan [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Defined contribution plan, vesting period	10 years
Supplemental Retirement Plan, Defined Contribution Plan, New Balance Annual Additions [Member]
Significant Accounting Policies [Line Items]
Defined contribution plan, interest credit percentage	4.50%
Supplemental Retirement Plan, Defined Contribution Plan, New Balance Annual Additions [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Defined contribution plan, service credit percentage	3.00%
Supplemental Retirement Plan, Defined Contribution Plan, New Balance Annual Additions [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Defined contribution plan, service credit percentage	5.00%
Supplemental Retirement Plan, Defined Contribution Plan, Old Balance Annual Additions [Member]
Significant Accounting Policies [Line Items]
Defined contribution plan, interest credit percentage	7.50%
Savings and Investment Plan, Defined Contribution Plan [Member]
Significant Accounting Policies [Line Items]
Defined contribution plan, minimum annual employee contributions per employee, percent	1.00%
Defined contribution plan, vesting period	5 years
Defined contribution plan, employer matched rate of employee contributions, percentage	50.00%
Defined contribution plan, employer matching contribution, percent	6.00%
Retirement Plan [Member]
Significant Accounting Policies [Line Items]
Defined benefit plan, interest credit rate	4.50%
Defined benefit plan, vesting period (years)	3 years
Retirement Plan [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Defined benefit plan, service credit percentage	3.00%
Retirement Plan [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Defined benefit plan, service credit percentage	5.00%
Service Based Awards [Member]
Significant Accounting Policies [Line Items]
Vesting period (years) for share options and awards	3 years
Market-Based Awards Relative To FTSE NAREIT U.S. Shopping Center Index [Member]
Significant Accounting Policies [Line Items]
Vesting period (years) for share options and awards	3 years
Percentage allocation of market based awards	50.00%
Market-Based Awards Relative To Three-Year Absolute TSR [Member]
Significant Accounting Policies [Line Items]
Vesting period (years) for share options and awards	3 years
Percentage allocation of market based awards	50.00%
Market based awards, hurdle comparison	6.00%
Share Options [Member]
Significant Accounting Policies [Line Items]
Maximum term of option award (years)	10 years
Market Based Awards [Member]
Significant Accounting Policies [Line Items]
Vesting period (years) for share options and awards	3 years
Building [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Real estate asset, estimated useful life	18 years
Building [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Real estate asset, estimated useful life	40 years
Parking Lot Surfacing And Equipment [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Real estate asset, estimated useful life	10 years
Parking Lot Surfacing And Equipment [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Real estate asset, estimated useful life	20 years
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Significant Accounting Policies [Line Items]
Concentrations of risk	2.60%
Houston Texas Geographic Concentration [Member] | Revenue Benchmark [Member]
Significant Accounting Policies [Line Items]
Concentrations of risk	20.00%
Other Parts of Texas Geographic Concentration [Member] | Revenue Benchmark [Member]
Significant Accounting Policies [Line Items]
Concentrations of risk	9.30%
Ninety-Day London Interbank Offered Rate (LIBOR) [Member] | Supplemental Retirement Plan, Defined Contribution Plan, Old Balance Annual Additions [Member]
Significant Accounting Policies [Line Items]
Defined contribution plan, basis spread on variable rate	0.005
FLORIDA | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Significant Accounting Policies [Line Items]
Concentrations of risk	19.80%
CALIFORNIA | Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Significant Accounting Policies [Line Items]
Concentrations of risk	17.90%