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, 2012	Dec. 31, 2011
Equity Funds
Total other post-retirement plan assets	$ 225
Equity Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets	4
Equity Funds | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets	221
Equity Funds | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets	0
Fixed Income Funds
Total other post-retirement plan assets	6
Fixed Income Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets	6
Fixed Income Funds | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets	0
Fixed Income Funds | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets	0
Hedge Funds
Total other post-retirement plan assets	1
Hedge Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets	0
Hedge Funds | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets	1
Hedge Funds | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets	0
Equity Securities
Total other post-retirement plan assets	120	133
Equity Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets	120	133
Equity Securities | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets	0	0
Equity Securities | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets	0	0
Fixed Income Securities
Total other post-retirement plan assets	56	61
Fixed Income Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets	1	2
Fixed Income Securities | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets	55	59
Fixed Income Securities | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets	0	0
Commingled Funds | Money Market Funds
Total other post-retirement plan assets		12
Commingled Funds | Money Market Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets		0
Commingled Funds | Money Market Funds | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets		12
Commingled Funds | Money Market Funds | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets		0
Commingled Funds | Equity Funds
Total other post-retirement plan assets		159
Commingled Funds | Equity Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets		1
Commingled Funds | Equity Funds | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets		158
Commingled Funds | Equity Funds | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets		0
Commingled Funds | Fixed Income Funds
Total other post-retirement plan assets		6
Commingled Funds | Fixed Income Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets		0
Commingled Funds | Fixed Income Funds | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets		6
Commingled Funds | Fixed Income Funds | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets		0
Other Postretirement Benefit Plans, Defined Benefit
Total other post-retirement plan assets	426	379
Other Postretirement Benefit Plans, Defined Benefit | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets	149	144
Other Postretirement Benefit Plans, Defined Benefit | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets	277	235
Other Postretirement Benefit Plans, Defined Benefit | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets	0	0
Cash
Total other post-retirement plan assets	18	8
Cash | Quoted Prices in Active Markets for Identical Assets (Level 1)
Total other post-retirement plan assets	18	8
Cash | Significant Other Observable Inputs (Level 2)
Total other post-retirement plan assets	0	0
Cash | Significant Unobservable Inputs (Level 3)
Total other post-retirement plan assets	$ 0	$ 0