Benefit Plans, Fair Value of Plan Assets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 343		$ 294
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	75		67
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	268		227
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0		0
Cash and cash equivalents (a) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16	[1]	18	[1]
Cash and cash equivalents (a) [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[1]	0	[1]
Cash and cash equivalents (a) [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16	[1]	18	[1]
Cash and cash equivalents (a) [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[1]	0	[1]
U.S. equity funds (domestic) (e) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	23	[2]	94	[2],[3]
U.S. equity funds (domestic) (e) [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12	[2]	52	[2],[3]
U.S. equity funds (domestic) (e) [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	[2]	42	[2],[3]
U.S. equity funds (domestic) (e) [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[2]	0	[2],[3]
International equity funds (non-U.S.) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25	[2]	39	[2]
International equity funds (non-U.S.) [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[2]	0	[2]
International equity funds (non-U.S.) [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25	[2]	39	[2]
International equity funds (non-U.S.) [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[2]	0	[2]
Global equity funds (domestic and non-U.S.) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	42	[2]
Global equity funds (domestic and non-U.S.) [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[2]
Global equity funds (domestic and non-U.S.) [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	42	[2]
Global equity funds (domestic and non-U.S.) [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[2]
Fixed income long duration bonds (c) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	174	[4]	128	[4]
Fixed income long duration bonds (c) [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[4]	0	[4]
Fixed income long duration bonds (c) [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	174	[4]	128	[4]
Fixed income long duration bonds (c) [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[4]	0	[4]
Real return funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31	[5]	15	[5]
Real return funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	31	[5]	15	[5]
Real return funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[5]	0	[5]
Real return funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[5]	0	[5]
Absolute return funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	32	[5]	0	[5]
Absolute return funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	32	[5]	0	[5]
Absolute return funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	[5]	0	[5]
Absolute return funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	[5]	$ 0	[5]

[1] Cash and cash equivalents consist of cash on hand and a short-term investment fund. The short-term investment fund provides for safety of principal and daily liquidity and is valued using the net asset value (NAV) per share. These assets are classified as Level 2 investments.

[2] Equities consist of mutual funds and commingled investment funds that invest in equity securities. Commingled fund values reflect the net asset value per share, derived from the quoted prices in active markets of the underlying securities. Mutual funds are classified as Level 1 investments; commingled funds are classified as Level 2 investments.

[3] We have presented prior year U.S. large cap and U.S. small/mid cap asset categories in U.S. equity funds (domestic) asset category in order to conform to current year presentation.

[4] Fixed income assets represent securities primarily invested in corporate, government related, mortgage and asset backed securities with a focus on long duration issues. Individual fixed income securities are generally priced on the basis of evaluated prices from independent pricing services. Such prices are monitored and provided by an independent, third-party custodial firm responsible for safekeeping plan assets. All fixed income securities are classified as Level 2 investments.

[5] Other assets consist of investments in mutual funds that invest in a broad set of asset classes designed to provide the potential for real returns in excess of U.S. inflation or a target return regardless of market conditions. These assets are categorized as Level 1 investments.