Fair Value Measurements, Nonrecurring (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Total [Line Items]
Refining equipment, materials and engineering costs	$ 5	$ 4
Goodwill		36
Losses (gains) on asset impairments and sales of assets	51	20	12
Goodwill, impairment loss	0	10	43
Level 1 [Member]
Total [Line Items]
Refining equipment, materials and engineering costs	0	0
Goodwill		0
Level 2 [Member]
Total [Line Items]
Refining equipment, materials and engineering costs	0	0
Goodwill		0
Level 3 [Member]
Total [Line Items]
Refining equipment, materials and engineering costs	5	4
Goodwill		$ 36