Commitments and Contingencies - Additional Information (Detail) (Nonqualified Deferred Compensation Plan, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Nonqualified Deferred Compensation Plan
Commitments and Contingencies Disclosure [Line Items]
Defined Benefit Plan Contributions Percent Of Compensation	100.00%
Accumulated benefit obligation	$ 0.9	$ 1.0
Investments to fund a future liability, market value	$ 0.9	$ 1.0

For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

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This element represents the fair value of the face or notional amount of a contract right or obligation that meets the definition of an asset or liability reported in the financial statements of the entity.

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