A Summary of Option Activity Under Plan (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Shares
Outstanding, beginning of year	53,714
Granted	0
Exercised	0
Forfeited or expired	0
Outstanding, end of year	53,714
Exercisable, end of year	0
Weighted - Average Exercise Price
Outstanding, beginning of year	$ 10.34
Granted	$ 0
Exercised	$ 0
Forfeited or expired	$ 0
Outstanding, end of year	$ 10.34
Exercisable, end of year	$ 0
Weighted - Average Remaining Contractual Term (Years)
Weighted average remaining contractual term	2 years 2 months 12 days
Exercisable, end of year	0 years
Aggregate Intrinsic Value
Outstanding, end of year	$ 0
Exercisable, end of year	$ 0

The intrinsic value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units, as calculated by applying the disclosed pricing methodology.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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