Discontinued Operations (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate	$ 0	$ 5,854,000	$ 10,870,000	$ 5,854,000
Schedule of components from discontinued operations [Abstract]
Rental revenues	0	1,006,000	608,000	2,347,000
Property operating expenses	0	(459,000)	(260,000)	(1,024,000)
Depreciation and amortization	0	(261,000)	(94,000)	(636,000)
Income from real estate sold	0	286,000	254,000	687,000
Gain on sale of real estate	0	5,854,000	10,870,000	5,854,000
Internal disposition costs	0	(589,000)	(1,087,000)	(589,000)
Gain on sale after disposition costs	5,265,000		9,783,000
Income from discontinued operations	0	5,551,000	10,037,000	5,952,000
Tierra Del Sol Norte [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Units in the community	156		156
Sales price of communities sold			17,200,000
Gain on sale of real estate			7,000,000
Schedule of components from discontinued operations [Abstract]
Gain on sale of real estate			7,000,000
Alpine Country [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Units in the community	108		108
Sales price of communities sold			11,100,000
Gain on sale of real estate			3,900,000
Schedule of components from discontinued operations [Abstract]
Gain on sale of real estate			$ 3,900,000