Discontinued Operations (Schedule Of Properties Identified As Held For Sale) (Details) (USD $)				12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Apr. 10, 2013 19 Skyline Drive [Member]	Dec. 31, 2012 16 And 18 Sentry Park West [Member]	Mar. 31, 2013 Assets Held-for-sale [Member] sqft item	Mar. 31, 2013 Assets Held-for-sale [Member] 19 Skyline Drive [Member] sqft item		Mar. 31, 2013 Assets Held-for-sale [Member] 55 Corporate Drive [Member] sqft item		Mar. 31, 2013 Assets Held-for-sale [Member] 51 Imclone Drive [Member] sqft item	Mar. 31, 2013 Assets Held-for-sale [Member] 16 Sentry Park West [Member] item sqft		Mar. 31, 2013 Assets Held-for-sale [Member] 18 Sentry Park West [Member] sqft item		Mar. 31, 2013 Assets Held-for-sale [Member] 777 Passaic Avenue [Member] sqft item	Mar. 31, 2013 Assets Held-for-sale [Member] 200 Riser Road [Member] sqft item
Long Lived Assets Held-for-sale [Line Items]
Number of Buildings					7	1	[1],[2]	1	[1]	1	1	[3]	1	[3]	1	1
Rentable Square Feet					1,065,401	248,400	[1],[2]	204,057	[1]	63,213	93,093	[3]	95,010	[3]	75,000	286,628
Gross Book Value					$ 149,206,000	$ 37,798,000	[1],[2]	$ 48,256,000	[1]	$ 5,375,000	$ 14,781,000	[3]	$ 15,713,000	[3]	$ 7,346,000	$ 19,937,000
Accumulated Depreciation					(38,652,000)	(14,713,000)	[1],[2]	(2,060,000)	[1]	(398,000)	(5,654,000)	[3]	(6,041,000)	[3]	(3,779,000)	(6,007,000)
Valuation Allowance					(7,080,000)	(7,080,000)	[1],[2]
Net Book Value	103,474,000	60,863,000			103,474,000	16,005,000	[1],[2]	46,196,000	[1]	4,977,000	9,127,000	[3]	9,672,000	[3]	3,567,000	13,930,000
Sales proceeds			16,000,000
Impairment charge				$ 8,400,000

[1] Property identified as held for sale as of December 31, 2012.

[2] On April 10, 2013, the Company sold this property for approximately $16 million.

[3] The Company recorded an impairment charge on these properties of a total of $8.4 million at December 31, 2012.