Income Taxes - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
Feb. 28, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Line Items]
Federal net operating loss carryforward		$ 31,200,000
Estimated tax deferral		127,000,000
Proceeds from refund of overpaid federal tax	80,900,000
Uncertain tax benefits that, if recognized, would affect effective tax rate		1,000,000	1,200,000
Recognized interest and penalties related to unrecognized tax benefits		126,000	41,000	35,000
Accrued interest and penalties		$ 234,000	$ 374,000

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from employee bonuses.

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This element represents the total of accruals as of the date of the statement of financial position for interest recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties.

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- Definition

This element represents the total of interest expense recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties in the period in which the entity claims or expects to claim a tax position, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties.

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