Real Estate Transactions (Schedule Of Properties Which Commenced Initial Operations) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 item sqft
14 Sylvan Way [Member]
Number of Buildings	1	[1]
Rentable Square Feet	203,506	[1]
Development Costs Incurred by Company	$ 50,661	[1]
Development Costs Incurred Per Square Foot	248.94	[1]
Land [Member]
Development Costs Incurred by Company	13,100
Leases [Member]
Development Costs Incurred by Company	$ 4,300

[1] Development costs included approximately $13.1 million in land costs and $4.3 million in leasing costs. Amounts are as of June 30, 2013.