Derivative and Other Financial Instruments Derivative and Other Financial Instruments (Offsetting of Derivative Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amounts Recognized in the Balance Sheet, Derivative Assets	$ 29	$ 22
Gross Amounts Not Offset in the Balance Sheet, Derivative Assets	5	7
Net Amount, Derivative Assets	24	15
Gross Amounts Recognized in the Balance Sheet, Derivative Liabilities	53	30
Gross Amounts Not Offset in the Balance Sheet, Derivative Liabilities	5	7
Net Amount, Derivative Liabilities	$ 48	$ 23

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset against an obligation to return collateral under a master netting arrangement.

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- Definition

Fair value of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset against a right to receive collateral under a master netting arrangement.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details