Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Benefits [Member]
Funded status of the pension and other postretirement benefit plans [Abstract]
Benefit obligation, beginning of year	$ 2,114	$ 1,900
Service cost	79	75	73
Interest cost	120	112	104
Actuarial loss	256	92
Benefits paid	(75)	(63)
Foreign currency translation effect	0	(2)
Benefit obligation, end of year	2,494	2,114	1,900
Plan assets at fair value	2,001	1,922
Funded status at end of year, included in other liabilities	493	192
Other Postretirement Benefits [Member]
Funded status of the pension and other postretirement benefit plans [Abstract]
Benefit obligation, beginning of year	392	338
Service cost	11	11	10
Interest cost	22	21	19
Actuarial loss	40	32
Benefits paid	(11)	(11)
Foreign currency translation effect	0	1
Benefit obligation, end of year	454	392	338
Plan assets at fair value	73	65
Funded status at end of year, included in other liabilities	$ 381	$ 327