Derivative and Hedging Activities Derivative and Hedging Activities - Fair Value of Recurring Assets and Liabilities Table (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ (799)	$ (649)
Commodity contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Asset	16	40
Derivative Liability	(742)	(593)
Interest rate contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	(80)	(98)
Foreign currency contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign Currency Contracts, Asset, Fair Value Disclosure	7	2
Fair Value, Inputs, Level 1 [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	0	0
Fair Value, Inputs, Level 1 [Member] | Commodity contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Fair Value, Inputs, Level 1 [Member] | Interest rate contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign currency contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign Currency Contracts, Asset, Fair Value Disclosure	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	(292)	(171)
Fair Value, Inputs, Level 2 [Member] | Commodity contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Asset	10	25
Derivative Liability	(229)	(100)
Fair Value, Inputs, Level 2 [Member] | Interest rate contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	(80)	(98)
Fair Value, Inputs, Level 2 [Member] | Foreign currency contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign Currency Contracts, Asset, Fair Value Disclosure	7	2
Fair Value, Inputs, Level 3 [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	(507)	(478)
Fair Value, Inputs, Level 3 [Member] | Commodity contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Derivative Asset	6	15
Derivative Liability	(513)	(493)
Fair Value, Inputs, Level 3 [Member] | Interest rate contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign currency contracts
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Foreign Currency Contracts, Asset, Fair Value Disclosure	$ 0	$ 0