Retirement Plans (Fair Value Of Our Other Post-Retirement Plan Assets by Category and the Corresponding Level within the Fair Value Hierarchy) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Equity Securities [Member]
Total other post-retirement plan assets	$ 133	$ 192
Equity Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Total other post-retirement plan assets	133	192
Equity Securities [Member] | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets
Fixed Income Securities [Member]
Total other post-retirement plan assets	61	53
Fixed Income Securities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Total other post-retirement plan assets	2	1
Fixed Income Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Total other post-retirement plan assets	59	52
Fixed Income Securities [Member] | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets
Other Investments [Member] | Insurance Deposit Agreements [Member]
Total other post-retirement plan assets		5
Other Investments [Member] | Insurance Deposit Agreements [Member] | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets		5
Commingled Funds [Member] | Money Market Funds [Member]
Total other post-retirement plan assets	12	65
Commingled Funds [Member] | Money Market Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Total other post-retirement plan assets	12	65
Commingled Funds [Member] | Money Market Funds [Member] | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets
Commingled Funds [Member] | Equity Funds [Member]
Total other post-retirement plan assets	159	33
Commingled Funds [Member] | Equity Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Total other post-retirement plan assets	1	23
Commingled Funds [Member] | Equity Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Total other post-retirement plan assets	158	10
Commingled Funds [Member] | Equity Funds [Member] | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets
Commingled Funds [Member] | Fixed Income Funds [Member]
Total other post-retirement plan assets	6	12
Commingled Funds [Member] | Fixed Income Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Total other post-retirement plan assets	6	12
Commingled Funds [Member] | Fixed Income Funds [Member] | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets
Other Post-Retirement Benefits [Member]
Total other post-retirement plan assets	379	389
Other Post-Retirement Benefits [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Total other post-retirement plan assets	144	245
Other Post-Retirement Benefits [Member] | Significant Other Observable Inputs (Level 2) [Member]
Total other post-retirement plan assets	235	139
Other Post-Retirement Benefits [Member] | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets		5
Cash [Member]
Total other post-retirement plan assets	8	29
Cash [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Total other post-retirement plan assets	8	29
Cash [Member] | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets