Employee Retirement Benefits (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Pension Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	$ 16	$ 15	$ 32	$ 30
Interest cost	25	25	49	51
Expected return on plan assets	(60)	(60)	(119)	(120)
Amortization of transition obligation	0	0	0	0
Amortization of prior service benefit	(1)	(1)	(1)	(2)
Net periodic benefit (income) cost	(20)	(21)	(39)	(41)
Other Benefits [Member]
Net periodic benefit (income) cost [Abstract]
Service cost	2	1	3	3
Interest cost	5	6	11	11
Expected return on plan assets	(1)	(1)	(1)	(1)
Amortization of transition obligation	1	1	1	2
Amortization of prior service benefit	0	0	0	0
Net periodic benefit (income) cost	$ 7	$ 7	$ 14	$ 15