Employee Retirement Benefits (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	$ 16	$ 15	$ 48	$ 45
Interest cost	25	25	74	76
Expected return on plan assets	(60)	(60)	(179)	(180)
Amortization of transition obligation	0	0	0	0
Amortization of prior service benefit	(1)	(1)	(2)	(3)
Net periodic benefit (income) cost	(20)	(21)	(59)	(62)
Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	2	1	5	4
Interest cost	5	6	16	17
Expected return on plan assets	(1)	(1)	(2)	(2)
Amortization of transition obligation	1	1	2	3
Amortization of prior service benefit	0	0	0	0
Net periodic benefit (income) cost	$ 7	$ 7	$ 21	$ 22