Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Percentage of ordinary taxable income to be distributed for real estate investment trust qualification	90.00%
Percentage of taxable income to be distributed for federal income tax assumption	100.00%
Tax expenses	$ 0.1	$ 0.1	$ 1.6
Net deferred tax asset	8.5	8.7
U.S federal NOLs	10.6
U.S. state NOLs	10.8
U.S. federal and state NOLs, expiration period	2020 through 2031
Valuation allowance	$ 8.5	$ 8.9

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards.

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- Definition

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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- Definition

The amount of the valuation allowance recorded as of the balance sheet date pertaining to the specified deferred tax asset for which an assessment was made that it is more likely than not that all or a portion of such deferred tax asset will not be realized through related deductions on future tax returns.

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