Pension And Other Postretirement Benefits (Schedule Of Fair Value Of Plan Assets) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan, Fair Value of Plan Assets	$ 2,360		$ 1,975
Pension Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets	2,039		1,694		1,632
Pension Benefits [Member] | Equity Securities Domestic [Member]
Defined Benefit Plan, Fair Value of Plan Assets	367	[1]	411	[1]
Pension Benefits [Member] | Equity Securities International [Member]
Defined Benefit Plan, Fair Value of Plan Assets	254	[2]	196	[2]
Pension Benefits [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets	1,256	[3]	939	[4]
Pension Benefits [Member] | Private Equity [Member]
Defined Benefit Plan, Fair Value of Plan Assets	56		64
Pension Benefits [Member] | Real Estate [Member]
Defined Benefit Plan, Fair Value of Plan Assets	74		65
Pension Benefits [Member] | Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets	32	[5]	19	[5]
Other Postretirement Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets	321		281		275
Other Postretirement Benefits [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets	115	[6]	101	[6]
Other Postretirement Benefits [Member] | Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets	7		6
Other Postretirement Benefits [Member] | Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets	199	[7]	174	[7]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member]
Defined Benefit Plan, Fair Value of Plan Assets	744		633
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Pension Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets	451		376
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Pension Benefits [Member] | Equity Securities Domestic [Member]
Defined Benefit Plan, Fair Value of Plan Assets	169	[1]	165	[1]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Pension Benefits [Member] | Equity Securities International [Member]
Defined Benefit Plan, Fair Value of Plan Assets	250	[2]	192	[2]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Pension Benefits [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets		[3]		[4]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Pension Benefits [Member] | Private Equity [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Pension Benefits [Member] | Real Estate [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Pension Benefits [Member] | Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets	32	[5]	19	[5]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets	293		257
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Other Postretirement Benefits [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets	115	[6]	101	[6]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Other Postretirement Benefits [Member] | Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets	7		6
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Other Postretirement Benefits [Member] | Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets	171	[7]	150	[7]
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan, Fair Value of Plan Assets	1,442		1,177
Significant Other Observable Inputs (Level 2) [Member] | Pension Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets	1,414		1,153
Significant Other Observable Inputs (Level 2) [Member] | Pension Benefits [Member] | Equity Securities Domestic [Member]
Defined Benefit Plan, Fair Value of Plan Assets	170	[1]	221	[1]
Significant Other Observable Inputs (Level 2) [Member] | Pension Benefits [Member] | Equity Securities International [Member]
Defined Benefit Plan, Fair Value of Plan Assets	1	[2]	2	[2]
Significant Other Observable Inputs (Level 2) [Member] | Pension Benefits [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets	1,243	[3]	930	[4]
Significant Other Observable Inputs (Level 2) [Member] | Pension Benefits [Member] | Private Equity [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Significant Other Observable Inputs (Level 2) [Member] | Pension Benefits [Member] | Real Estate [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Significant Other Observable Inputs (Level 2) [Member] | Pension Benefits [Member] | Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets		[5]		[5]
Significant Other Observable Inputs (Level 2) [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets	28		24
Significant Other Observable Inputs (Level 2) [Member] | Other Postretirement Benefits [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets		[6]		[6]
Significant Other Observable Inputs (Level 2) [Member] | Other Postretirement Benefits [Member] | Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Significant Other Observable Inputs (Level 2) [Member] | Other Postretirement Benefits [Member] | Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets	28	[7]	24	[7]
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan, Fair Value of Plan Assets	174		165		150
Significant Unobservable Inputs (Level 3) [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets	13		9		3
Significant Unobservable Inputs (Level 3) [Member] | Private Equity [Member]
Defined Benefit Plan, Fair Value of Plan Assets	56		64		62
Significant Unobservable Inputs (Level 3) [Member] | Real Estate [Member]
Defined Benefit Plan, Fair Value of Plan Assets	74		65		55
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets	31		27		30
Significant Unobservable Inputs (Level 3) [Member] | Pension Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets	174		165
Significant Unobservable Inputs (Level 3) [Member] | Pension Benefits [Member] | Equity Securities Domestic [Member]
Defined Benefit Plan, Fair Value of Plan Assets	28	[1]	25	[1]
Significant Unobservable Inputs (Level 3) [Member] | Pension Benefits [Member] | Equity Securities International [Member]
Defined Benefit Plan, Fair Value of Plan Assets	3	[2]	2	[2]
Significant Unobservable Inputs (Level 3) [Member] | Pension Benefits [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets	13	[3]	9	[4]
Significant Unobservable Inputs (Level 3) [Member] | Pension Benefits [Member] | Private Equity [Member]
Defined Benefit Plan, Fair Value of Plan Assets	56		64
Significant Unobservable Inputs (Level 3) [Member] | Pension Benefits [Member] | Real Estate [Member]
Defined Benefit Plan, Fair Value of Plan Assets	74		65
Significant Unobservable Inputs (Level 3) [Member] | Pension Benefits [Member] | Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets		[5]		[5]
Significant Unobservable Inputs (Level 3) [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Significant Unobservable Inputs (Level 3) [Member] | Other Postretirement Benefits [Member] | Fixed Income [Member]
Defined Benefit Plan, Fair Value of Plan Assets		[6]		[6]
Significant Unobservable Inputs (Level 3) [Member] | Other Postretirement Benefits [Member] | Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Significant Unobservable Inputs (Level 3) [Member] | Other Postretirement Benefits [Member] | Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets		[7]		[7]

[1] Predominantly includes domestic common stock and commingled funds.

[2] Predominantly includes foreign common and preferred stock and warrants.

[3] Predominantly includes corporate bonds, government bonds, municipal/provincial bonds, collateralized mortgage obligations and commingled funds.

[4] Predominantly includes corporate bonds, government bonds, municipal bonds, and commingled funds.

[5] Predominantly includes cash investment in short-term investment funds.

[6] Includes fixed income commingled funds.

[7] Includes domestic and international commingled funds.