Employee Retirement Plans (Schedule Of Defined Benefit Plan Assets Measured At Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	$ 2,975		$ 2,770
Commodities [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	92	[1]	90	[1]
Insurance Contracts [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	6		5
Cash Equivalents [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	57		97
Fixed Income [Member] | U.S. Corporate Bonds [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	1,624		1,446
Fixed Income [Member] | International Fixed Income [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	245		173
Equity Securities [Member] | U.S. Companies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	313		315
Equity Securities [Member] | International Companies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	314		312
Private Equity [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	221	[2]	241	[2]
Real Estate [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	103	[3]	91	[3]
Level 1 [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	671		392
Level 1 [Member] | Cash Equivalents [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	57		97
Level 1 [Member] | Fixed Income [Member] | U.S. Corporate Bonds [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	151
Level 1 [Member] | Fixed Income [Member] | International Fixed Income [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	182
Level 1 [Member] | Equity Securities [Member] | U.S. Companies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	185		215
Level 1 [Member] | Equity Securities [Member] | International Companies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	96		80
Level 2 [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	1,974		2,041
Level 2 [Member] | Commodities [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	92	[1]	90	[1]
Level 2 [Member] | Fixed Income [Member] | U.S. Corporate Bonds [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	1,473		1,446
Level 2 [Member] | Fixed Income [Member] | International Fixed Income [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	63		173
Level 2 [Member] | Equity Securities [Member] | U.S. Companies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	128		100
Level 2 [Member] | Equity Securities [Member] | International Companies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	218		232
Level 3 [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	330		337
Level 3 [Member] | Insurance Contracts [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	6		5		5
Level 3 [Member] | Private Equity [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	221	[2]	241	[2]	234
Level 3 [Member] | Real Estate [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	$ 103	[3]	$ 91	[3]	$ 74

[1] This category includes investments in energy, industrial metals, precious metals, agricultural and livestock primarily through futures, options, swaps, and exchange traded funds

[2] This category includes venture capital, leverage buyouts and distressed debt limited partnerships invested primarily in U.S. companies. The inputs are valued by internally generated Discounted Cash Flow Analysis and comparable sale analysis

[3] This category includes industrial, office, apartments, hotels, infrastructure, and retail investments which are limited partnerships predominately in the U.S. The inputs are valued by internally generated Discounted Cash Flow Analysis; compare sale analysis and periodic external appraisals