Deferred Charges, Goodwill And Other Assets, Net (Schedule Of Deferred Charges, Goodwill And Other Assets) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Aug. 31, 2017
Deferred Charges, Goodwill And Other Assets [Line Items]        
Deferred leasing costs $ 199,515 $ 220,947    
Deferred financing costs - unsecured revolving credit facility [1] 4,945 5,400    
Deferred charges, gross 204,460 226,347    
Accumulated amortization (98,956) (107,359)    
Deferred charges, net 105,504 118,988    
Notes receivable [2] 50,167 13,251    
In-place lease values, related intangibles and other assets, net [3],[4] 102,757 72,046    
Goodwill [5] 2,945 2,945    
Prepaid expenses and other assets, net [6] 80,947 60,720    
Total deferred charges, goodwill and other assets, net 342,320 267,950    
Lease revenue 501,334 506,877 $ 487,041  
Acquired Above And Below Market Lease Intangibles [Member]        
Deferred Charges, Goodwill And Other Assets [Line Items]        
Lease revenue 7,900 $ 1,900 $ 200  
Acquisition-related Costs [Member]        
Deferred Charges, Goodwill And Other Assets [Line Items]        
Net sales proceeds held by qualified intermediary $ 26,900      
Notes Receivable 5.85 Interest Rate [Member]        
Deferred Charges, Goodwill And Other Assets [Line Items]        
Mortgage loan, maturity date Jul. 01, 2019      
Interest rate 5.85%      
Notes receivable $ 45,700     $ 44,700
Loan extension period 3 months      
Interest-Free Notes Receivable [Member]        
Deferred Charges, Goodwill And Other Assets [Line Items]        
Mortgage loan, maturity date Apr. 01, 2023      
Notes receivable $ 2,500      
Disposal Group, Not Discontinued Operations [Member] | Buyer [Member] | Bergen Portfolio [Member]        
Deferred Charges, Goodwill And Other Assets [Line Items]        
Notes receivable $ 65,000      
[1] Deferred financing costs related to all other debt liabilities (other than for the unsecured revolving credit facility) are netted against those debt liabilities for all periods presented. See Note 2: Significant Accounting Policies - Deferred Financing Costs.
[2] Includes as of December 31, 2017: a mortgage receivable with a balance of $45.7 million (acquired in August 2017) which bears interest at 5.85 percent and matures in July 2019, with a three-month extension option and an interest-free note receivable with a net present value of $2.5 million which matures in April 2023. The Company believes these balances are fully collectible.
[3] In accordance with ASC 805, Business Combinations, the Company recognizes rental revenue of acquired above and below market lease intangibles over the terms of the respective leases. The impact of amortizing the acquired above and below-market lease intangibles increased revenue by approximately $7.9 million, $1.9 million and $0.2 million for the years ended December 31, 2017, 2016 and 2015, respectively. The following table summarizes, as of December 31, 2017, the scheduled amortization of the Company's acquired above and below-market lease intangibles for each of the five succeeding years (dollars in thousands).
[4] The value of acquired in-place lease intangibles are amortized to expense over the remaining initial terms of the respective leases. The impact of the amortization of acquired in-place lease values is included in depreciation and amortization expense and amounted to approximately $32.2 million, $14.3 million and $1.4 million for the years ended December 31, 2017, 2016 and 2015, respectively. The following table summarizes, as of December 31, 2017, the scheduled amortization of the Company's acquired in-place lease values for each of the five succeeding years (dollars in thousands).
[5] All goodwill is attributable to the Company's Multi-family Services segment.
[6] Includes as of December 31, 2017, $26.9 million of proceeds from property sales held by a qualified intermediary.