Real Estate Transactions (Schedule Of Properties Which Commenced Initial Operations) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 sqft item
Real Estate Properties [Line Items]
Number of Buildings	2
Rentable Square Feet	220,242
Garage Parking Spaces	850
Development Costs Incurred by Company	$ 122,591
14 Sylvan Way [Member]
Real Estate Properties [Line Items]
Number of Buildings	1
Rentable Square Feet	203,506
Development Costs Incurred by Company	51,484	[1]
Development Costs Per Parking Space	253.00
Port Imperial South 4/5 [Member]
Real Estate Properties [Line Items]
Number of Buildings	1
Rentable Square Feet	16,736
Garage Parking Spaces	850
Development Costs Incurred by Company	71,107	[2]
Land [Member] | 14 Sylvan Way [Member]
Real Estate Properties [Line Items]
Development Costs Incurred by Company	13,000
Land [Member] | Port Imperial South 4/5 [Member]
Real Estate Properties [Line Items]
Development Costs Incurred by Company	13,100
Leases [Member] | 14 Sylvan Way [Member]
Real Estate Properties [Line Items]
Development Costs Incurred by Company	$ 4,300

[1] Development costs included approximately $13.0 million in land costs and $4.3 million in leasing costs. Amounts are as of September 30, 2013.

[2] Development costs included approximately $13.1 million in land costs. Amounts are as of September 30, 2013.