Recent Transactions (Schedule Of Properties Which Commenced Initial Operations) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) item
Real Estate Properties [Line Items]
Number of Apartment Units | item	1,317
Total Development Costs Incurred	$ 457,984
Unconsolidated Joint Venture Multi-Family Properties [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item	2,922
Unconsolidated Joint Venture Hotel [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item	350
145 Front At City Square [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item	365
Total Development Costs Incurred	$ 97,483
Signature Place At Morris Plains [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item	197
Total Development Costs Incurred	$ 56,715
Portside 5/6 [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item	296
Total Development Costs Incurred	$ 114,694
Expected costs	$ 700
Riverhouse 11 At Port Imperial [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item	295
Total Development Costs Incurred	$ 130,369
Expected costs	$ 1,200
Residence Inn By Marriott (Phase I) [Member]
Real Estate Properties [Line Items]
Number of Apartment Units | item	164
Total Development Costs Incurred	$ 58,723
Land [Member] | 145 Front At City Square [Member]
Real Estate Properties [Line Items]
Total Development Costs Incurred	4,400
Land [Member] | Signature Place At Morris Plains [Member]
Real Estate Properties [Line Items]
Total Development Costs Incurred	900
Construction Loan [Member] | 145 Front At City Square [Member]
Real Estate Properties [Line Items]
Expected costs	1,100
Construction Loan [Member] | Residence Inn By Marriott (Phase I) [Member]
Real Estate Properties [Line Items]
Expected costs	$ 20,100