Property (Details Textual) (USD $)	12 Months Ended				0 Months Ended	3 Months Ended		0 Months Ended		0 Months Ended			12 Months Ended		12 Months Ended		12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	Apr. 20, 2012 Discontinued operation [Member] Georgia Door Sales Distribution Center [Member]	Mar. 31, 2012 Discontinued operation [Member] Georgia Door Sales Distribution Center [Member]	Mar. 16, 2012 Discontinued operation [Member] Georgia Door Sales Distribution Center [Member] sqft	Apr. 11, 2012 Discontinued operation [Member] Marketplace at Northglenn [Member]	Jul. 11, 2012 Discontinued operation [Member] Marketplace at Northglenn [Member] sqft	Jul. 11, 2012 Discontinued operation [Member] Marketplace at Northglenn [Member] Mortgage notes payable [Member]	Mar. 23, 2012 Discontinued operation [Member] Metropolitan Park North [Member] sqft	Mar. 23, 2012 Discontinued operation [Member] Metropolitan Park North [Member] Mortgage notes payable [Member]	Dec. 31, 2010 Discontinued operation [Member] Havertys Furniture [Member]	Apr. 15, 2010 Discontinued operation [Member] Havertys Furniture [Member] sqft	Dec. 31, 2010 Discontinued operation [Member] 25850 S. Ridgeland [Member]	Apr. 15, 2010 Discontinued operation [Member] 25850 S. Ridgeland [Member] sqft	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2012 111 Sutter Street [Member]		Dec. 04, 2012 111 Sutter Street [Member] sqft	Dec. 31, 2012 Dignity Health Office Portfolio [Member] properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Real Estate Properties																						15
Interest Rate	4.75%	[1]																	5.58%	[1]		5.75%
Fair Value Inputs, Long-term Revenue Growth Rate																	3.00%	7.00%
Fair Value Inputs, Cap Rate	6.25%
Fair Value Inputs, Discount Rate	7.75%
Business Acquisition, Pro Forma Revenue	$ 86,471,000		$ 89,229,000
Business Acquisition, Pro Forma Net Income (Loss)	(1,591,000)		10,203,000
Property (Textual) [Abstract]
Number of square foot of industrial center							254,000		439,000		187,000			808,000		719,000					286,000
Sale of property					5,000									35,000,000		19,060,000
Gain (loss) on sale of property	(117,000)		0	822,000	117,000			6					113,000		709,000
Extinguishment of debt								66,480,000			56,513,000
Gain (loss) on sale of property	14,607,000		0	(242,000)						2,908,000	6,018,000	5,773,000
Recognized impairment charges	$ 913,000		$ 14,934,000	$ 25,639,000	$ 913,000	$ 913,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners																						22.00%

[1] The seller of 111 Sutter Street provided a short-term financing at closing at the prime rate (3.25% at December 31, 2012) plus 150 basis points.