Geographic Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Geographic Information [Line Items]
Revenues	$ 134,252	$ 136,264	$ 128,954
Long-Lived Assets	39,978	33,853	33,572
North America
Geographic Information [Line Items]
Revenues	87,347	82,126	74,206
Long-Lived Assets	28,652	23,256	22,290
United States
Geographic Information [Line Items]
Revenues	76,418	71,165	63,318
Long-Lived Assets	23,987	19,311	17,423
Canada
Geographic Information [Line Items]
Revenues	9,523	9,525	9,351
Long-Lived Assets	2,674	2,525	3,456
Mexico/Other
Geographic Information [Line Items]
Revenues	1,406	1,436	1,537
Long-Lived Assets	1,991	1,420	1,411
Total Europe
Geographic Information [Line Items]
Revenues	27,918	35,280	36,774
Long-Lived Assets	6,976	6,834	7,756
United Kingdom
Geographic Information [Line Items]
Revenues	9,214	9,486	9,172
Long-Lived Assets	1,668	1,721	1,817
Germany
Geographic Information [Line Items]
Revenues	8,281	8,717	7,139
Long-Lived Assets	2,770	3,060	3,395
Italy
Geographic Information [Line Items]
Revenues	1,633	3,038	3,656
Long-Lived Assets	3	3	3
France
Geographic Information [Line Items]
Revenues	1,964	2,806	2,754
Long-Lived Assets	183	102	105
Spain
Geographic Information [Line Items]
Revenues	1,735	2,189	2,235
Long-Lived Assets	1,500	1,185	1,211
Russia
Geographic Information [Line Items]
Revenues	0	1,913	2,041
Long-Lived Assets	0	0	228
Belgium
Geographic Information [Line Items]
Revenues	892	1,288	1,539
Long-Lived Assets	824	735	964
Other
Geographic Information [Line Items]
Revenues	4,199	5,843	8,238
Long-Lived Assets	28	28	33
All Other
Geographic Information [Line Items]
Revenues	18,987	18,858	17,974
Long-Lived Assets	$ 4,350	$ 3,763	$ 3,526