Inventories (Narrative) (Details) (Crude Oil And Refined Product Inventories [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Toledo Refinery And Related Inventory [Member]
Inventories [Line Items]
LIFO inventory profits before tax		$ 535
LIFO inventory profits after tax		321
Philadelphia And Marcus Hook Refineries [Member]
Inventories [Line Items]
LIFO inventory profits before tax	497	42
LIFO inventory profits after tax	302	26
Hedging losses, pre-tax	30
Hedging losses, after-tax	$ 18