Segment Reporting (Schedule Of Selected Results Of Operations And Asset Information) (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Segment Reporting Information [Line Items]          
Total revenues $ 77,650 $ 87,390 $ 232,357 $ 264,261  
Total operating and interest expenses 85,863 72,079 227,393 222,516  
Equity in earnings (loss) of unconsolidated joint ventures 1,373 (113) (281) (882)  
Net operating income (loss) (6,840) 15,198 4,683 40,863  
Total assets 5,190,743   5,190,743   $ 5,292,798
Total long-lived assets 4,730,553   4,730,553   4,763,193
Total investments in unconsolidated joint ventures 194,779   194,779   209,091
Commercial And Other Real Estate [Member]          
Segment Reporting Information [Line Items]          
Total revenues 38,288 40,211 112,597 135,803  
Total operating and interest expenses 16,562 18,200 54,035 60,254  
Equity in earnings (loss) of unconsolidated joint ventures 493 307 (1) 1,540  
Net operating income (loss) 22,219 22,318 58,561 77,089  
Total assets 1,912,093   1,912,093   2,178,321
Total long-lived assets 1,714,697   1,714,697   1,947,053
Total investments in unconsolidated joint ventures 7,864   7,864   7,367
Multiple-Family Real Estate & Services [Member]          
Segment Reporting Information [Line Items]          
Total revenues 37,658 46,453 118,739 127,521  
Total operating and interest expenses 26,772 23,989 71,689 67,606  
Equity in earnings (loss) of unconsolidated joint ventures 880 (420) (280) (2,422)  
Net operating income (loss) 11,766 22,044 46,770 57,493  
Total assets 3,265,827   3,265,827   3,079,409
Total long-lived assets 3,015,868   3,015,868   2,812,306
Total investments in unconsolidated joint ventures 186,915   186,915   201,724
Corporate & Other [Member]          
Segment Reporting Information [Line Items]          
Total revenues 1,704 726 1,021 937  
Total operating and interest expenses 42,529 29,890 101,669 94,656  
Net operating income (loss) (40,825) $ (29,164) (100,648) $ (93,719)  
Total assets 12,823   12,823   35,068
Total long-lived assets $ (12)   $ (12)   $ 3,834