Assets Held for Sale and Discontinued Operations - Income Attributable to Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Assets Held For Sale [Line Items]
Rental income and recoveries	$ 623	$ 33,541
Rental expenses	(174)	(9,085)
Depreciation and amortization expense	(164)	(11,544)
Interest expense	(38)	(391)
Income attributable to disposed properties and assets held for sale	247	12,521
Net gains on dispositions	5,834	11,249
Total discontinued operations	$ 6,081	$ 23,770

After tax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its disposal.

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Amount of interest expense allocated to disposal group, including a discontinued operation.

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- Definition

Amount of income (loss) from a disposal group, net of income tax before extraordinary items allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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