Discontinued Operations and Investment Properties Held for Sale (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues:
Rental income	$ 2,741	$ 5,531	$ 11,875	$ 18,957
Tenant recovery income	(565)	687	165	2,095
Other property income	34	15	59	68
Total revenues	2,210	6,233	12,099	21,120
Expenses:
Property operating expenses	332	988	1,197	2,354
Real estate taxes	(503)	487	326	2,132
Depreciation and amortization	952	2,206	4,380	7,851
Provision for impairment of investment properties	11,507	1,379	11,507	31,752
Loss on lease terminations	0	85	40	87
General and administrative expenses	0	0	0	34
Interest expense	1,709	1,465	4,374	5,736
Other expense	1	1	0	4
Total expenses	13,998	6,611	21,824	49,950
Loss from discontinued operations, net	$ (11,788)	$ (378)	$ (9,725)	$ (28,830)