Changes In Business And Other Matters (Provision Of Asset Write-Downs And Other Matters) (Details) (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Changes In Business And Other Matters [Line Items]
Pretax provisions	$ 1,977	$ 64
After-tax provisions for asset write-downs and other matters	1,186	39
Philadelphia And Marcus Hook Refineries [Member]
Changes In Business And Other Matters [Line Items]
Pretax provisions	1,959
After-tax provisions for asset write-downs and other matters	1,175
Business Improvement Initiatives [Member]
Changes In Business And Other Matters [Line Items]
Pretax provisions	13	47
After-tax provisions for asset write-downs and other matters	8	28
Eagle Point Refinery [Member]
Changes In Business And Other Matters [Line Items]
Pretax provisions	5	33
After-tax provisions for asset write-downs and other matters	3	20
MTBE Coverage Settlement [Member]
Changes In Business And Other Matters [Line Items]
Pretax provisions		(16)
After-tax provisions for asset write-downs and other matters		$ (9)