Segment Information, Geographic Information by Country for Revenue and Long-Lived Assets (Details) (USD $)	3 Months Ended											12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating revenues by geographic area
Entity-wide revenue, major customer amount												$ 0	$ 0	$ 0
Operating revenues	34,695,000,000	34,726,000,000	34,662,000,000	35,167,000,000	[1]	34,673,000,000	[2]	33,713,000,000	[3]	31,293,000,000	26,308,000,000	139,250,000,000	125,987,000,000	82,233,000,000
Geographic information by country for long-lived assets
Total long-lived assets	27,587,000,000					26,495,000,000						27,587,000,000	26,495,000,000
U.S. [Member]
Operating revenues by geographic area
Operating revenues												100,733,000,000	98,806,000,000	67,392,000,000
Geographic information by country for long-lived assets
Long-lived assets in the U.S.	23,760,000,000					22,317,000,000						23,760,000,000	22,317,000,000
Canada [Member]
Operating revenues by geographic area
Operating revenues												10,376,000,000	10,110,000,000	6,945,000,000
Geographic information by country for long-lived assets
Long-lived assets in foreign countries	2,639,000,000					2,372,000,000						2,639,000,000	2,372,000,000
U. K. [Member]
Operating revenues by geographic area
Operating revenues												10,779,000,000	4,297,000,000	149,000,000
Geographic information by country for long-lived assets
Long-lived assets in foreign countries	1,110,000,000					848,000,000						1,110,000,000	848,000,000
Aruba [Member]
Geographic information by country for long-lived assets
Long-lived assets in foreign countries	41,000,000					958,000,000						41,000,000	958,000,000
Other countries [Member]
Operating revenues by geographic area
Operating revenues												17,362,000,000	12,774,000,000	7,747,000,000
Ireland [Member]
Geographic information by country for long-lived assets
Long-lived assets in foreign countries	$ 37,000,000					$ 0						$ 37,000,000	$ 0

[1] The operations of the Aruba Refinery were suspended in March 2012.

[2] Includes the operations related to the Meraux Acquisition beginning October 1, 2011.

[3] Includes the operations related to the Pembroke Acquisition beginning August 1, 2011.