Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Examination [Line Items]
Reduction in taxes payable as result of exercise and vesting of equity based compensation	$ 9,603	$ 8,990	$ 15,609
Excess tax benefit associated with equity based compensation	5,033	4,763	11,997
Increase (reduction) to tax expense	2,602		1,547
Additional Increase to tax expense			1,580
Recorded a reduction to tax expense due to reversal of certain tax contingencies			563
Accrual for interest, net of tax		$ 29

Tax benefit associated with any equity-based compensation plan other than an employee stock ownership plan (ESOP). The tax benefit results from the deduction by the entity on its tax return for an award of stock that exceeds the cumulative compensation cost for common stock or preferred stock recognized for financial reporting. Includes any resulting tax benefit that exceeds the previously recognized deferred tax asset (excess tax benefits).

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This element represents the amount of interest expense accrued as of the date of the statement of financial position 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.

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