Summary of Activity for Stock Option Plans (Detail) (USD $)	6 Months Ended
Jun. 30, 2011
Number of Stock Options
Stock options outstanding, beginning of year	12,443,676
Exercised	(349,923)
Expired/forfeited	(2,172,863)
Stock options outstanding, end of period	9,920,890
Options exercisable, end of period	9,920,890
Weighted Average Exercise Price
Stock options outstanding, beginning of year	$ 15.75
Exercised	$ 12.54
Expired/forfeited	$ 18.24
Stock options outstanding, end of period	$ 15.32
Options exercisable, end of period	$ 15.32

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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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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

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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.

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The weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated during the reporting period due to noncompliance with plan terms during the reporting period.

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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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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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The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

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