Segment Reporting (Schedule Of Selected Results Of Operations And Asset Information) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Segment Reporting Information [Line Items]          
Total revenues $ 162,766 $ 149,227 $ 312,653 $ 302,150  
Total operating and interest expenses [1] 101,877 101,186 199,183 209,479  
Equity in earnings (loss) of unconsolidated joint ventures (3,298) (614) (3,349) (2,168)  
Net operating income (loss) [2] 57,591 47,427 110,121 90,503  
Total assets 5,076,494   5,076,494   $ 4,296,766
Total long-lived assets [3] 4,361,753   4,361,753   3,616,534
Total investments in unconsolidated joint ventures 315,110   315,110   320,047
Corporate & Other [Member]          
Segment Reporting Information [Line Items]          
Total revenues [4] (3,336) (3,181) (6,308) (4,924)  
Total operating and interest expenses [1],[4] 23,137 21,473 42,309 44,521  
Net operating income (loss) [2],[4] (26,473) (24,654) (48,617) (49,445)  
Total assets [4] 16,053   16,053   47,769
Total long-lived assets [3],[4] (7,653)   (7,653)   (5,933)
Real Estate - Commercial And Other [Member]          
Segment Reporting Information [Line Items]          
Total revenues 139,319 133,768 272,531 270,721  
Total operating and interest expenses [1] 60,306 64,368 123,169 133,378  
Equity in earnings (loss) of unconsolidated joint ventures (18) 1,405 394 1,082  
Net operating income (loss) [2] 78,995 70,805 149,756 138,425  
Total assets 3,414,214   3,414,214   3,344,396
Total long-lived assets [3] 3,009,316   3,009,316   2,999,820
Total investments in unconsolidated joint ventures 85,367   85,367   81,549
Real Estate - Multi Family [Member]          
Segment Reporting Information [Line Items]          
Total revenues 17,299 9,219 27,694 18,205  
Total operating and interest expenses [1] 8,256 5,920 14,110 11,335  
Equity in earnings (loss) of unconsolidated joint ventures (3,982) (2,100) (4,768) (3,331)  
Net operating income (loss) [2] 5,061 1,199 8,816 3,539  
Total assets 1,631,796   1,631,796   887,394
Total long-lived assets [3] 1,354,755   1,354,755   618,038
Total investments in unconsolidated joint ventures 227,948   227,948   237,493
Multi Family Services [Member]          
Segment Reporting Information [Line Items]          
Total revenues 9,484 [5] 9,421 [6] 18,736 [5] 18,148 [6]  
Total operating and interest expenses [1] 10,178 [7] 9,425 [8] 19,595 [7] 20,245 [8]  
Equity in earnings (loss) of unconsolidated joint ventures 702 81 1,025 81  
Net operating income (loss) [2] 8 77 166 (2,016)  
Total assets 14,431   14,431   17,207
Total long-lived assets [3] 5,335   5,335   4,609
Total investments in unconsolidated joint ventures 1,795   1,795   $ 1,005
Fee revenue 2,200 3,600      
Salary reimbursements earned     3,900 6,300  
Management fee $ 4,300 $ 1,700      
Salary reimbursement expenses     $ 7,900 $ 3,100  
[1] Total operating and interest expenses represent the sum of: real estate taxes; utilities; operating services; direct construction costs; real estate services expenses; general and administrative, acquisition related costs and interest expense (net of interest income). All interest expense, net of interest and other investment income, (including for property-level mortgages) is excluded from segment amounts and classified in Corporate & Other for all periods.
[2] Net operating income represents total revenues less total operating and interest expenses (as defined in Note "a"), plus equity in earnings (loss) of unconsolidated joint ventures, for the period.
[3] Long-lived assets are comprised of net investment in rental property, unbilled rents receivable and goodwill.
[4] Corporate & Other represents all corporate-level items (including interest and other investment income, interest expense, non-property general and administrative expense, construction services revenue and direct construction costs) as well as intercompany eliminations necessary to reconcile to consolidated Company totals.
[5] Includes $2.2 million and $3.9 million of fees and salary reimbursements earned for the three and six months ended June 30, 2017, from the multi-family real estate segment, which are eliminated in consolidation.
[6] Includes $3.6 million and $6.3 million of fees and salary reimbursements earned for the three and six months ended June 30, 2016, from the multi-family real estate segment, which are eliminated in consolidation.
[7] Includes $4.3 million and $7.9 million of management fees and salary reimbursement expenses for the three and six months ended June 30, 2017, from the multi-family real estate segment, which are eliminated in consolidation.
[8] Includes $1.7 million and $3.1 million of management fees and salary reimbursement expenses for the three and six months ended June 30, 2016, from the multi-family real estate segment, which are eliminated in consolidation.