Discontinued Operations (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended					3 Months Ended	0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 19, 2012 Portland Portfolio [Member] property acre		May 31, 2012 26200 Enterprise Way [Member]	Sep. 21, 2012 110 & 112 Hidden Lake Circle Buildings [Member]	Mar. 28, 2013 1111 Durham Avenue [Member]	Mar. 31, 2013 1111 Durham Avenue [Member]	May 01, 2013 1200 Enclave Parkway [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain/(Loss) on Sale	$ 0	$ (254,000)	$ 16,258,000	$ 27,583,000	$ 17,823,000	[1]	$ 10,013,000	$ (259,000)	$ (9,000)		$ 16,267,000
Net Sales Proceeds			49,326,000	74,845,000	43,832,000	[1]	24,412,000	25,595,000	3,752,000		45,574,000
Number of Real Estate Properties Sold					4
Area of Land (in acres)					18.19
Impairment loss	0	0	(6,402,000)	0						(6,400,000)
Sale price									4,000,000
Revenues:
Rental income	516,000	2,388,000	2,693,000	8,403,000
Tenant reimbursements	91,000	410,000	650,000	1,298,000
Revenue	607,000	2,798,000	3,343,000	9,701,000
Expenses:
Property operating costs	316,000	1,262,000	1,448,000	3,834,000
Depreciation	141,000	732,000	687,000	2,379,000
Amortization	21,000	159,000	138,000	527,000
General and administrative	0	38,000	2,000	47,000
Expenses	478,000	2,191,000	2,275,000	6,787,000
Other income (expense):
Interest and other income/(expense)	(1,000)	0	24,000	0
Net recoveries of casualty loss	0	0	17,000	0
Other income (expense)	(1,000)	0	41,000	0
Operating income, excluding gain/(loss) on sale	128,000	607,000	1,109,000	2,914,000
Income from discontinued operations	$ 128,000	$ 353,000	$ 10,965,000	$ 30,497,000

[1] The Portland Portfolio consisted of four office properties known as the Deschutes building, the Rhein building, the Rogue building, and the Willamette building, as well as 18.19 acres of adjoining, undeveloped land.