Discontinued Operations (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of real estate	$ (10,870,000)	$ 0
Schedule of components from discontinued operations [Abstract]
Rental revenues	608,000	1,340,000
Property operating expenses	(260,000)	(563,000)
Depreciation and amortization	(94,000)	(373,000)
Income from real estate sold	254,000	404,000
Gain on sale of real estate	10,870,000	0
Internal disposition costs	(1,087,000)	0
Income from discontinued operations	10,037,000	404,000
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
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
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)