Price Risk Management Activities, Hedging Instruments by Consolidated Balance Sheet Location (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Values of Derivative Instruments
Total derivative assets, net	$ 1,086	$ 1,215
Total derivative liabilities, net	1,040	1,209
Designated as Hedging Instrument [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset		94
Derivative liability, fair value, gross liability		79
Designated as Hedging Instrument [Member] | Future [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	14	77
Derivative asset, fair value, gross liability	28	64
Designated as Hedging Instrument [Member] | Swap [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset		15
Derivative asset, fair value, gross liability		13
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		2
Derivative asset, fair value, gross liability		2
Not Designated as Hedging Instrument [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	1,072	1,121
Derivative liability, fair value, gross liability	1,012	1,130
Not Designated as Hedging Instrument [Member] | Future [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	1,022	1,066
Derivative asset, fair value, gross liability	953	1,073
Not Designated as Hedging Instrument [Member] | Swap [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative liability, fair value, gross asset	5	32
Derivative liability, fair value, gross liability	11	46
Not Designated as Hedging Instrument [Member] | Swap [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	17	9
Derivative asset, fair value, gross liability	15	6
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
Derivative asset, fair value, gross liability	1
Not Designated as Hedging Instrument [Member] | Commodity Option [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative liability, fair value, gross asset	0	1
Derivative liability, fair value, gross liability	1	0
Not Designated as Hedging Instrument [Member] | Commodity Option [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	5	1
Derivative asset, fair value, gross liability	3	4
Not Designated as Hedging Instrument [Member] | Commodity Option [Member] | Prepaid Expenses and Other Current Assets [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	2
Derivative asset, fair value, gross liability	1
Not Designated as Hedging Instrument [Member] | Physical Purchase Contracts [Member] | Inventories [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	13	11
Derivative asset, fair value, gross liability	5	0
Not Designated as Hedging Instrument [Member] | RINs Fixed-Price Contracts [Member] | Prepaid Expenses and Other Current Assets [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset	7
Derivative asset, fair value, gross liability	19
Not Designated as Hedging Instrument [Member] | Foreign Currency Contract [Member] | Accrued Expenses [Member]
Fair Values of Derivative Instruments
Derivative liability, fair value, gross asset	0	0
Derivative liability, fair value, gross liability	3	1
Not Designated as Hedging Instrument [Member] | Foreign Currency Contract [Member] | Trade Accounts Receivable [Member]
Fair Values of Derivative Instruments
Derivative asset, fair value, gross asset		1
Derivative asset, fair value, gross liability		$ 0