Stock Option Information (Detail) (Employee Stock Option, USD $)	3 Months Ended
Mar. 31, 2012
Employee Stock Option
Shares
Outstanding at beginning of year	9,357,000
Granted	535,000
Exercised	(44,000)
Forfeited or expired	(1,072,000)
Outstanding at end of year	8,776,000
Weighted-average exercise price
Outstanding at beginning of year	$ 36.71
Granted	$ 35.63
Exercised	$ 27.89
Forfeited or expired	$ 35.36
Outstanding at end of year	$ 36.86

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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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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 combined weighted average exercise price associated with stock options during the period that have either lapsed or been forfeited.

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Net number of share options (or share units) granted during the period.

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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 stock options awarded under the plan 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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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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