Price Risk Management Activities, Hedging Instruments by Consolidated Balance Sheet Location (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Fair Values of Derivative Instruments
Total derivative assets, net	$ 2,274	$ 1,980
Total derivative liabilities, net	2,349	1,970
Designated as Hedging Instrument [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	254	300
Derivative liability, fair value, gross liability	274	286
Designated as Hedging Instrument [Member] | Future [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	161	264
Derivative liability, fair value, gross asset	188	240
Designated as Hedging Instrument [Member] | Swap [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	89
Derivative liability, fair value, gross asset	83
Designated as Hedging Instrument [Member] | Swap [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross liability	4	36
Derivative liability, fair value, gross liability	3	46
Not Designated as Hedging Instrument [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	2,020	1,680
Derivative liability, fair value, gross liability	2,075	1,684
Not Designated as Hedging Instrument [Member] | Future [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	1,949	1,636
Derivative liability, fair value, gross asset	1,957	1,624
Not Designated as Hedging Instrument [Member] | Swap [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	46
Derivative liability, fair value, gross asset	48
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	1	4
Derivative liability, fair value, gross asset	0	2
Not Designated as Hedging Instrument [Member] | Swap [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross liability	22	38
Derivative liability, fair value, gross liability	31	51
Not Designated as Hedging Instrument [Member] | Commodity Option [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	1	2
Derivative liability, fair value, gross asset	0	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
Derivative liability, fair value, gross liability		2
Not Designated as Hedging Instrument [Member] | Forward Contracts [Member] | Inventories [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross liability	0	0
Derivative liability, fair value, gross liability	36	2
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	1
Derivative liability, fair value, gross asset	0
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross liability	0	0
Derivative liability, fair value, gross liability	$ 3	$ 3