Investments In Unconsolidated Joint Ventures (Narrative) (Detail) (USD $)		1 Months Ended
	Jul. 25, 2012 Annapolis Junction Building Six [Member] sqft	Sep. 27, 2012 300 Billerica Road [Member] sqft	Sep. 27, 2012 Company [Member]
Schedule of Equity Method Investments [Line Items]
Interest in Joint venture	50.00%
Net rentable area	120,000	111,000
Contractual sale price		$ 12,200,000
Carrying value of debt assumed in sale		7,500,000
Cash proceeds from the sale of real estate property		4,300,000	2,800,000
Repayment of notes receivable			2,400,000
Gain on sales of real estate		$ 1,000,000	$ 200,000