Employee Retirement Plans (Schedule Of Defined Benefit Plan Assets Measured At Fair Value) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	$ 2,770		$ 2,690
Commodities [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	90	[1]	104	[1]
Insurance Contracts [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	5		5
Cash Equivalents [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	97		45
Fixed Income [Member] | U.S. Treasuries/Agencies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets			103
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	1,446		953
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	173		392
Fixed Income [Member] | Other Fixed Income [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets			146
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	315		312
Equity Securities [Member] | International Companies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	312		322
Private Equity [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	241	[2]	234	[2]
Real Estate [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	91	[3]	74	[3]
Level 1 [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	392		280
Level 1 [Member] | Cash Equivalents [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	97		15
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	215		220
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	80		45
Level 2 [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	2,041		2,097
Level 2 [Member] | Commodities [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	90	[1]	104	[1]
Level 2 [Member] | Cash Equivalents [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets			30
Level 2 [Member] | Fixed Income [Member] | U.S. Treasuries/Agencies [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets			103
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	1,446		953
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	173		392
Level 2 [Member] | Fixed Income [Member] | Other Fixed Income [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets			146
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	100		92
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	232		277
Level 3 [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	337		313
Level 3 [Member] | Insurance Contracts [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	5		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	241	[2]	234	[2]	222
Level 3 [Member] | Real Estate [Member]
Schedule Of Defined Benefit Plan Of Assets Measured At Fair Value [Line Items]
Fair value of plan assets	$ 91	[3]	$ 74	[3]	$ 61

[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 the 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.