Investments In Unconsolidated Joint Ventures (Summary Of Unconsolidated Joint Ventures) (Details) $ in Thousands				1 Months Ended	9 Months Ended
	Feb. 28, 2019 USD ($)	Jan. 31, 2019 USD ($) item	Jan. 30, 2019 USD ($)	Oct. 31, 2019 USD ($)	Sep. 30, 2019 USD ($) ft² item	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					208
Carrying Value					$ 213,499		$ 232,750
Purchase price of property					$ 109,338	$ 132,252
Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Company's Effective Ownership %					20.00%
Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Company's Effective Ownership %					85.00%
Crystal House [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of interest in developable land					50.00%
Number of units available for development | item					295
Number of approved units available for development | item					252
PI North - Riverwalk C [Member] | Construction Loan [Member]
Schedule of Equity Method Investments [Line Items]
Maximum borrowing capacity					$ 112,000
Urby At Harborside [Member] | Construction/Permanent Loan [Member]
Schedule of Equity Method Investments [Line Items]
Company's Effective Ownership %					85.00%
Red Bank [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					836
Residual ownership interest					20.00%
Percentage of interest sold	50.00%
Gain on sale	$ 900
The Shops At 40 Park Property [Member] | Metropolitan At 40 Park [Member]
Schedule of Equity Method Investments [Line Items]
Rentable Square Feet (sf) | ft²					50,973
Balance					$ 6,067
Property Debt, Interest Rate, Spread Over LIBOR					2.25%
Residual ownership interest					25.00%
Mortgage loan, maturity month and year					October 2019
The Shops At 40 Park Property [Member] | Metropolitan At 40 Park [Member] | Subsequent Event [Member]
Schedule of Equity Method Investments [Line Items]
Mortgage loan, maturity month and year				October 2021
Lofts At 40 Park Property [Member] | Metropolitan At 40 Park [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					59
Indirect ownership interest					50.00%
Number of stories | item					5
Lofts At 40 Park Property [Member] | Metropolitan At 40 Park [Member] | Construction Loan [Member]
Schedule of Equity Method Investments [Line Items]
Mortgage loan, maturity month and year					February 2020
Lofts At 40 Park Property [Member] | Metropolitan At 40 Park [Member] | Subsequent Event [Member]
Schedule of Equity Method Investments [Line Items]
Property Debt, Interest Rate, Spread Over LIBOR				1.50%
Lofts At 40 Park Property [Member] | Metropolitan At 40 Park [Member] | Subsequent Event [Member] | Construction Loan [Member]
Schedule of Equity Method Investments [Line Items]
Balance				$ 13,145
Property Debt, Interest Rate, Spread Over LIBOR				2.50%
Maximum borrowing capacity				$ 13,950
Metropolitan Property [Member] | Metropolitan At 40 Park [Member]
Schedule of Equity Method Investments [Line Items]
Balance					$ 35,378
Property Debt, Interest Rate					3.25%
Mortgage loan, maturity month and year					September 2020
Unconsolidated Joint Venture Multi-Family Properties [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					2,611
Unconsolidated Joint Venture Multi-Family Properties [Member] | Marbella Tower Urban Renewal Associates LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item		311
Company's Effective Ownership %			24.27%
Balance		$ 117,000	$ 74,700
Property Debt, Interest Rate, Spread Over LIBOR		4.20%
Percentage of additional interest acquired		50.00%	50.00%
Repayment of mortgage loans		$ 74,700
Purchase price of property		$ 77,500
Mortgage loan, maturity month and year					August 2026
Unconsolidated Joint Venture Multi-Family Properties [Member] | Metropolitan At 40 Park [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					189
Company's Effective Ownership %					25.00%
Carrying Value					$ 7,346		7,679
Balance					$ 54,590
Unconsolidated Joint Venture Multi-Family Properties [Member] | RiverTrace At Port Imperial [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					316
Company's Effective Ownership %					22.50%
Carrying Value					$ 7,541		8,112
Balance					$ 82,000
Property Debt, Maturity Date					Nov. 10, 2026
Property Debt, Interest Rate					3.21%
Unconsolidated Joint Venture Multi-Family Properties [Member] | Crystal House [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					825
Company's Effective Ownership %					25.00%
Carrying Value					$ 28,903		29,570
Balance					$ 160,342
Property Debt, Maturity Date					Apr. 01, 2020
Property Debt, Interest Rate					3.17%
Unconsolidated Joint Venture Multi-Family Properties [Member] | PI North - Riverwalk C [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					360
Company's Effective Ownership %					40.00%
Carrying Value					$ 35,474		27,175
Balance					$ 15,252
Property Debt, Maturity Date					Dec. 06, 2021
Property Debt, Interest Rate					2.75%
Unconsolidated Joint Venture Multi-Family Properties [Member] | Marbella II [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					311
Company's Effective Ownership %					24.27%
Carrying Value							15,414
Unconsolidated Joint Venture Multi-Family Properties [Member] | Riverpark At Harrison [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					141
Company's Effective Ownership %					45.00%
Carrying Value					$ 1,032		1,272
Balance					$ 29,403
Property Debt, Maturity Date					Aug. 01, 2025
Property Debt, Interest Rate					3.70%
Unconsolidated Joint Venture Multi-Family Properties [Member] | Station House [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					378
Company's Effective Ownership %					50.00%
Carrying Value					$ 36,190		37,675
Balance					$ 97,279
Property Debt, Maturity Date					Jul. 01, 2033
Property Debt, Interest Rate					4.82%
Unconsolidated Joint Venture Multi-Family Properties [Member] | Urby At Harborside [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					762
Company's Effective Ownership %					85.00%
Carrying Value					$ 80,673		85,317
Balance					$ 192,000
Property Debt, Maturity Date					Aug. 01, 2029
Property Debt, Interest Rate					5.197%
Unconsolidated Joint Venture Multi-Family Properties [Member] | PI North - Land [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					836
Company's Effective Ownership %					20.00%
Carrying Value					$ 1,678		1,678
Unconsolidated Joint Venture Multi-Family Properties [Member] | Liberty Landing [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					850
Company's Effective Ownership %					50.00%
Carrying Value					$ 337		337
Unconsolidated Joint Venture Multi-Family Properties [Member] | Hillsborough 206 [Member]
Schedule of Equity Method Investments [Line Items]
Rentable Square Feet (sf) | ft²					160,000
Company's Effective Ownership %					50.00%
Carrying Value					$ 1,962		1,962
Unconsolidated Joint Venture Office Buildings [Member]
Schedule of Equity Method Investments [Line Items]
Rentable Square Feet (sf) | ft²					200,000
Unconsolidated Joint Venture Office Buildings [Member] | Red Bank [Member]
Schedule of Equity Method Investments [Line Items]
Rentable Square Feet (sf) | ft²					92,878
Company's Effective Ownership %					50.00%
Carrying Value							3,127
Gain on sale	$ 900
Unconsolidated Joint Venture Office Buildings [Member] | 12 Vreeland Road [Member]
Schedule of Equity Method Investments [Line Items]
Rentable Square Feet (sf) | ft²					139,750
Company's Effective Ownership %					50.00%
Carrying Value					$ 7,300		7,019
Balance					$ 6,681
Property Debt, Maturity Date					Jul. 01, 2023
Property Debt, Interest Rate					2.87%
Unconsolidated Joint Venture Office Buildings [Member] | Offices At Crystal Lake [Member]
Schedule of Equity Method Investments [Line Items]
Rentable Square Feet (sf) | ft²					106,345
Company's Effective Ownership %					31.25%
Carrying Value					$ 3,507		3,442
Balance					$ 3,514
Property Debt, Maturity Date					Nov. 01, 2023
Property Debt, Interest Rate					4.76%
Unconsolidated Joint Venture Other Property [Member]
Schedule of Equity Method Investments [Line Items]
Carrying Value					$ 213,499		232,750
Balance					$ 741,061
Unconsolidated Joint Venture Other Property [Member] | Riverwalk Retail [Member]
Schedule of Equity Method Investments [Line Items]
Rentable Square Feet (sf) | ft²					30,745
Company's Effective Ownership %					20.00%
Carrying Value					$ 1,476		1,539
Unconsolidated Joint Venture Other Property [Member] | Hyatt Regency Jersey City [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Units | item					351
Company's Effective Ownership %					50.00%
Carrying Value							112
Balance					$ 100,000
Property Debt, Maturity Date					Oct. 01, 2026
Property Debt, Interest Rate					3.668%
Unconsolidated Joint Venture Other Property [Member] | Other [Member]
Schedule of Equity Method Investments [Line Items]
Carrying Value					$ 80		$ 1,320