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

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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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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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Long-Term Incentive Plans (Outstanding Stock Options) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2010	Dec. 31, 2009
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options, Outstanding	5,963,268	6,425,073	6,650,947		7,044,820
Number of Options, Exercisable	1,751,173	2,211,878	2,050,252
Weighted Average Remaining Contractual Life in Years, Stock Options Outstanding	2 years 7 months 6 days
Weighted Average Exercise Price, Stock Options Outstanding	$ 19.0485	$ 21.3330	$ 22.1713		$ 25.3110
Weighted Average Exercise Price, Stock Options Exercisable	$ 45.0174	$ 46.1478	$ 53.1172	$ 5.05
Aggregate Intrinsic Value, Stock Options Outstanding	$ 9
$4.02-$12.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Average Exercise Price, Minimum	$ 4.02
Range of Average Exercise Price, Maximum	$ 12.50
Number of Options, Outstanding	4,550,000
Number of Options, Exercisable	350,000
Weighted Average Remaining Contractual Life in Years, Stock Options Outstanding	3 years 11 days
Weighted Average Exercise Price, Stock Options Outstanding	$ 7.8101
Aggregate Intrinsic Value, Stock Options Outstanding	9
$36.69-$55.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Average Exercise Price, Minimum	$ 36.69
Range of Average Exercise Price, Maximum	$ 55.60
Number of Options, Outstanding	409,707
Number of Options, Exercisable	401,612
Weighted Average Remaining Contractual Life in Years, Stock Options Outstanding	3 months 22 days
Weighted Average Exercise Price, Stock Options Outstanding	$ 39.7103
$57.10-$70.86 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Average Exercise Price, Minimum	$ 57.10
Range of Average Exercise Price, Maximum	$ 70.86
Number of Options, Outstanding	1,003,561
Number of Options, Exercisable	999,561
Weighted Average Remaining Contractual Life in Years, Stock Options Outstanding	1 year 7 months 10 days
Weighted Average Exercise Price, Stock Options Outstanding	$ 61.5665
Exercisable [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life in Years, Stock Options Exercisable	1 year 7 months 13 days
Weighted Average Exercise Price, Stock Options Exercisable	$ 45.0174
Aggregate Intrinsic Value, Stock Options Exercisable	1
Exercisable [Member] \| $4.02-$12.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life in Years, Stock Options Exercisable	3 years 1 month 13 days
Weighted Average Exercise Price, Stock Options Exercisable	$ 4.0200
Aggregate Intrinsic Value, Stock Options Exercisable	$ 1
Exercisable [Member] \| $36.69-$55.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life in Years, Stock Options Exercisable	3 months 26 days
Weighted Average Exercise Price, Stock Options Exercisable	$ 39.5601
Exercisable [Member] \| $57.10-$70.86 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Weighted Average Remaining Contractual Life in Years, Stock Options Exercisable	1 year 7 months 13 days
Weighted Average Exercise Price, Stock Options Exercisable	$ 61.5654