Inventories (Narrative) (Details) (USD $) In Millions	3 Months Ended	9 Months Ended	3 Months Ended
	Mar. 31, 2011 Toledo Refinery And Related Inventory [Member] Crude And Refined Product Inventories [Member]	Sep. 30, 2011 Toledo Refinery And Related Inventory [Member] Crude And Refined Product Inventories [Member]	Sep. 30, 2011 Frankford Facility [Member]
Inventories [Line Items]
LIFO inventory gains, pretax income (Loss)	$ 42	$ 535	$ 34
LIFO inventory gains, after-tax income (Loss)	$ 26	$ 321	$ 20