Summary of Activity for Stock Option Plans (Detail) - $ / shares	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Number of Stock Options
Stock options outstanding, beginning of year	2,400	58,560
Exercised	0	0
Expired	(2,400)
Stock options outstanding, end of year	0	2,400
Options exercisable at year-end	0
Weighted Average Exercise Price
Stock options outstanding, beginning of year	$ 16.88
Exercised	0
Expired	16.88
Stock options outstanding, end of year		$ 16.88
Options exercisable at year-end	$ 0

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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.

+ References

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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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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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

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