Fair Value Of Pension Plan Assets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 1,516	$ 1,411	$ 1,377
Pooled Funds - Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	10	7
Corporate Bonds And Other Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	794	758	751
Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	239	255	250
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	473	391	376
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	8,205	13,277
Pension Plans | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	210	119
Pension Plans | U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	186	272
Pension Plans | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	932	1,666
Pension Plans | Pooled Funds - Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1,673	4,755
Pension Plans | Cash and Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3,001	6,812
Pension Plans | Government Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1,440	1,170
Pension Plans | Pooled Funds - Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	963	1,515
Pension Plans | Corporate Bonds And Other Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1,969	3,019
Pension Plans | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	4,372	5,704
Pension Plans | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	342	351
Pension Plans | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	490	410
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	2,718	3,526
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	210	119
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	185	266
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	932	1,664
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Pooled Funds - Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	590	485
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Cash and Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1,917	2,534
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Government Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	209	571
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Pooled Funds - Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	285	230
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Corporate Bonds And Other Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	210	100
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	704	901
Quoted Prices In Active Markets For Identical Assets (Level 1) | Pension Plans | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	97	91
Significant Other Observable Inputs (Level 2) | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	3,971	8,340
Significant Other Observable Inputs (Level 2) | Pension Plans | U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1	6
Significant Other Observable Inputs (Level 2) | Pension Plans | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets		2
Significant Other Observable Inputs (Level 2) | Pension Plans | Pooled Funds - Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1,083	4,270
Significant Other Observable Inputs (Level 2) | Pension Plans | Cash and Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1,084	4,278
Significant Other Observable Inputs (Level 2) | Pension Plans | Government Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1,231	599
Significant Other Observable Inputs (Level 2) | Pension Plans | Pooled Funds - Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	668	1,278
Significant Other Observable Inputs (Level 2) | Pension Plans | Corporate Bonds And Other Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	965	2,161
Significant Other Observable Inputs (Level 2) | Pension Plans | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	2,864	4,038
Significant Other Observable Inputs (Level 2) | Pension Plans | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	6	5
Significant Other Observable Inputs (Level 2) | Pension Plans | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	17	19
Significant Unobservable Inputs (Level 3) | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1,516	1,411
Significant Unobservable Inputs (Level 3) | Pension Plans | Pooled Funds - Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	10	7
Significant Unobservable Inputs (Level 3) | Pension Plans | Corporate Bonds And Other Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	794	758
Significant Unobservable Inputs (Level 3) | Pension Plans | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	804	765
Significant Unobservable Inputs (Level 3) | Pension Plans | Real Estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	239	255
Significant Unobservable Inputs (Level 3) | Pension Plans | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 473	$ 391