Accounting for the Impairment or Disposal of Long-Lived Assets - Results of Operations for the Properties Held for Sale and Disposed (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Property, Plant and Equipment Impairment or Disposal [Abstract]
Revenues	$ 9,409,000	$ 21,961,000
Operating expenses	(4,090,000)	(9,555,000)
Interest and other income	27,000	95,000
Interest expense	(2,428,000)	(3,280,000)
Depreciation and amortization	(71,000)	(5,462,000)
Income before property dispositions	2,847,000	3,759,000
Gain on property dispositions	1,064,000	470,000
Net income	3,911,000	4,229,000
Proceeds from Sale of Property, Plant, and Equipment	$ 6,500,000	$ 3,600,000