Financial and Other Derivative Instruments Financial and Other Derivative Instruments (Netting Offsets Reconciliation to Balance Sheet) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Derivative Assets, Current	$ 79	$ 99
Derivative Assets, Noncurrent	17	27
Derivative Liabilities, Current	140	195
Derivative Liabilities, Noncurrent	16	43
Derivative Asset [Member]
Derivative [Line Items]
Derivative Assets, Current	841	691
Derivative Assets, Noncurrent	85	142
Derivative Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Current	899	773
Derivative Liabilities, Noncurrent	85	163
Counterparty Netting [Member]
Derivative [Line Items]
Derivative Assets, Current	(756)	(566)
Derivative Assets, Noncurrent	(68)	(115)
Derivative Liabilities, Current	756	566
Derivative Liabilities, Noncurrent	68	115
Collateral Adjustment [Member]
Derivative [Line Items]
Derivative Assets, Current	(6)	(26)
Derivative Assets, Noncurrent	0	0
Derivative Liabilities, Current	3	12
Derivative Liabilities, Noncurrent	$ 1	$ 5

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, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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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, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ 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, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ 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, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References+ Details