Summary of Activity for Stock Option Plans (Detail) (USD $)	3 Months Ended
Mar. 31, 2015
Number of Stock Options
Stock options outstanding, beginning of year	58,560
Exercised	0
Expired/forfeited	(26,160)
Stock options outstanding, end of period	32,400
Options exercisable, end of period	32,400
Weighted Average Exercise Price
Stock options outstanding, beginning of year	$ 18.04
Exercised	$ 0
Expired/forfeited	$ 17.91
Stock options outstanding, end of period	$ 18.15
Options exercisable, end of period	$ 18.15

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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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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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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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Weighted average price of options that were either forfeited or expired.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

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No definition available.

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Number of share options (or share units) exercised during the current period.

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