Segment Information, Geographic Information by Country for Revenue and Long-Lived Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating revenues by geographic area
Operating revenues	$ 27,859	$ 34,408	$ 34,914	$ 33,663	$ 34,429	$ 36,137	$ 34,034	[1]	$ 33,474	$ 130,844	$ 138,074	$ 138,393
Geographic information by country for long-lived assets
Long-lived assets	28,247				27,059					28,247	27,059
U.S. [Member]
Operating revenues by geographic area
Operating revenues										91,499	100,418	99,879
Geographic information by country for long-lived assets
Long-lived assets	24,710				23,572					24,710	23,572
Canada [Member]
Operating revenues by geographic area
Operating revenues										10,410	9,974	10,376
Geographic information by country for long-lived assets
Long-lived assets	2,250				2,260					2,250	2,260
U. K. and Ireland [Member]
Operating revenues by geographic area
Operating revenues										14,182	13,675	12,818
U.K. [Member]
Geographic information by country for long-lived assets
Long-lived assets	1,206				1,148					1,206	1,148
Other countries [Member]
Operating revenues by geographic area
Operating revenues										14,753	14,007	15,320
Aruba [Member]
Geographic information by country for long-lived assets
Long-lived assets	59				53					59	53
Ireland [Member]
Geographic information by country for long-lived assets
Long-lived assets	$ 22				$ 26					$ 22	$ 26

[1] The separation of our retail business was completed on May 1, 2013.