Investments In Unconsolidated Joint Ventures (Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	$ (127)	$ (6,081)	$ 18,788
Amortization of basis difference	903	792	436
Hillsborough 206 [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	16	(25)	(53)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Marbella I [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	205	334	231
Unconsolidated Joint Venture Multi-Family Properties [Member] | Metropolitan At 40 Park [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(455)	(311)	(317)
Unconsolidated Joint Venture Multi-Family Properties [Member] | RiverTrace At Port Imperial [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	154	196	(1,146)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Crystal House [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(874)	(923)	(870)
Unconsolidated Joint Venture Multi-Family Properties [Member] | PI North Pier Land [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(126)	(219)	(62)
Unconsolidated Joint Venture Multi-Family Properties [Member] | PI North - Riverwalk C [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures		(653)	(58)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Marbella II [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	35	93	(202)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverpark At Harrison [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(232)	(252)	(190)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Station House [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(2,096)	(1,793)	(2,440)
Unconsolidated Joint Venture Multi-Family Properties [Member] | Urby At Harborside [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(975)	(6,356)	(219)
Economic tax credit certificate income	$ 2,600
Period of venture agreement to sell economic tax credit	9 years
Annual proceeds from economic tax credit	$ 3,000
Total proceeds from economic tax credit	27,000
Unconsolidated Joint Venture Multi-Family Properties [Member] | Liberty Landing [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(5)	(15)	(80)
Unconsolidated Joint Venture Office Buildings [Member] | Red Bank [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(215)	238	448
Unconsolidated Joint Venture Office Buildings [Member] | 12 Vreeland Road [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	285	496	347
Unconsolidated Joint Venture Office Buildings [Member] | Offices At Crystal Lake [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	73	89	(15)
Unconsolidated Joint Venture Other Property [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(127)	(6,081)	18,788
Unconsolidated Joint Venture Other Property [Member] | Roseland/North Retail, L.L.C./ Riverwalk At Port Imperial [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	(86)	(81)	(52)
Unconsolidated Joint Venture Other Property [Member] | South Pier At Harborside / Hyatt Regency Jersey City On The Hudson [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	3,672	3,277	24,180
Unconsolidated Joint Venture Other Property [Member] | Other [Member]
Schedule of Equity Method Investments [Line Items]
Company's equity in earnings of unconsolidated joint ventures	$ 497	$ (176)	$ (714)