Summary Of Amount Reported as Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenue			$ 5,144	$ 6,332
Property operations and maintenance expense			(1,601)	(1,881)
Real estate tax expense			(561)	(798)
Depreciation and amortization expense			(787)	(1,058)
Net realized gain on sale of property	4,498		4,498
Total income from discontinued operations	$ 4,821	$ 922	$ 6,693	$ 2,595