Debt (Summary Of Debt Outstanding) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Mortgages payable	$ 474,379	$ 491,505
Revolving credit facility	0	41,000
Notes payable	279,027	320,265
Net unamortized debt issuance costs	(365)	(554)
Senior notes and debentures	2,404,279	2,401,440
Capital lease obligations	71,519	71,556
Total debt and capital lease obligations	3,229,204	3,284,766
Mortgages Payable
Debt Instrument [Line Items]
Principal balance	475,308	491,561
Net unamortized (discount)/premium and debt issuance costs	(929)	(56)
Notes Payable
Debt Instrument [Line Items]
Notes payable	279,392	320,819
Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	2,419,200	2,419,200
Net unamortized (discount)/premium and debt issuance costs	(14,921)	(17,760)
The Grove at Shrewsbury (West) \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 0	10,545
Interest rate	6.38%
Rollingwood Apartments \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 20,331	20,820
Interest rate	5.54%
The Shops at Sunset Place \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 64,453	66,603
Interest rate	5.624%
29th Place \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 4,117	4,341
Interest rate	5.91%
Sylmar Towne Center \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 17,006	17,362
Interest rate	5.39%
Plaza Del Sol \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 8,409	8,579
Interest rate	5.23%
THE AVENUE at White Marsh \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 52,705	52,705
Interest rate	3.35%
Montrose Crossing \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 69,310	71,054
Interest rate	4.20%
Azalea \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 40,000	40,000
Interest rate	3.73%
Bell Gardens \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 12,936	13,184
Interest rate	4.06%
Plaza El Segundo \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 125,000	125,000
Interest rate	3.83%
The Grove at Shrewsbury (East) \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 43,600	43,600
Interest rate	3.77%
Brook 35 \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 11,500	11,500
Interest rate	4.65%
Chelsea \| Mortgages Payable
Debt Instrument [Line Items]
Principal balance	$ 5,941	6,268
Interest rate	5.36%
Term Loan \| Notes Payable
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
Other Notes Payable	$ 275,000	275,000
Revolving credit facility \| Notes Payable
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.825%
Various \| Notes Payable
Debt Instrument [Line Items]
Interest rate	11.31%
Other Notes Payable	$ 4,392	4,819
2.55% notes \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 250,000	250,000
Interest rate	2.55%
3.00% notes \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 250,000	250,000
Interest rate	3.00%
2.75% notes \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 275,000	275,000
Interest rate	2.75%
3.95% notes \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 300,000	300,000
Interest rate	3.95%
7.48% debentures \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 29,200	29,200
Interest rate	7.48%
3.25% Senior notes \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 475,000	475,000
Interest rate	3.25%
6.82% medium term notes \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 40,000	40,000
Interest rate	6.82%
4.50% notes \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 550,000	550,000
Interest rate	4.50%
3.625% Senior notes \| Senior Notes and Debentures
Debt Instrument [Line Items]
Principal balance	$ 250,000	$ 250,000
Interest rate	3.625%

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

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