| 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 | |||||
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- Details 
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