Summary Of Option Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
Sep. 30, 2012
Options
Options, Outstanding Beginning Balance	15,556,786
Options, Granted	2,513
Options, Exercised	(1,887,878)
Options, Expired	(2,940,525)
Options, Outstanding Ending Balance	10,730,896
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding Beginning Balance	$ 38.13
Weighted Average Exercise Price, Granted	$ 35.94
Weighted Average Exercise Price, Exercised	$ 32.83
Weighted Average Exercise Price, Expired	$ 41.22
Weighted Average Exercise Price, Outstanding Ending Balance	$ 38.21
Weighted Average Remaining Life (years)
Weighted Average Remaining Life (years), Outstanding Ending Balance	1 year 3 months 7 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding Ending Balance	$ 500

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

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

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

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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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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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