Price Risk Management Activities, Hedging Instruments by Balance Sheet Location (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Fair Values of Derivative Instruments
Total derivative assets, net	$ 4,869	$ 3,326
Total derivative liabilities, net	4,970	3,599
Designated as Hedging Instrument [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	939	206
Derivative liability, fair value, gross liability	815	254
Designated as Hedging Instrument [Member] | Future [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	939	120
Derivative liability, fair value, gross asset	815	183
Designated as Hedging Instrument [Member] | Swap [Member] | Prepaid Expenses and Other Current Assets [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset		55
Derivative liability, fair value, gross asset		39
Designated as Hedging Instrument [Member] | Swap [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross liability		31
Derivative liability, fair value, gross liability		32
Not Designated as Hedging Instrument [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	3,930	3,120
Derivative liability, fair value, gross liability	4,155	3,345
Not Designated as Hedging Instrument [Member] | Future [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	3,700	2,717
Derivative liability, fair value, gross asset	3,777	2,914
Not Designated as Hedging Instrument [Member] | Swap [Member] | Prepaid Expenses and Other Current Assets [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	39	287
Derivative liability, fair value, gross asset	35	277
Not Designated as Hedging Instrument [Member] | Swap [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross liability	188	116
Derivative liability, fair value, gross liability	320	148
Not Designated as Hedging Instrument [Member] | Commodity Option [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	3
Derivative liability, fair value, gross asset	0
Not Designated as Hedging Instrument [Member] | Commodity Option [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross liability	0	0
Derivative liability, fair value, gross liability	$ 23	$ 6