Summary of Income from Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental income	$ 20,666	$ 25,520	$ 56,744
Operating and other expenses	(14,398)	(19,364)	(29,708)
Interest expense, net	(4,443)	(4,860)	(5,542)
Loss on extinguishment of debt	(3,880)
Depreciation expense	(3,603)	(5,064)	(13,805)
Income (loss) from discontinued operations	$ (5,658)	$ (3,768)	$ 7,689