Employee Benefit Plans (Components of Net Periodic Benefit Cost) (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]
Service cost	$ 23	$ 2	$ 44	$ 3
Interest cost	45	3	89	5
Expected return on plan assets	(35)	(3)	(69)	(5)
Amortization of unrecognized gain and prior service cost	(7)	(1)	(12)	(1)
Net periodic benefit costs	26	1	52	2
Other Postretirement Benefits [Member]
Service cost	12	8	24	15
Interest cost	32	29	63	58
Expected return on plan assets		(1)	(1)	(1)
Amortization of unrecognized gain and prior service cost	(1)	(3)	(1)	(6)
Net periodic benefit costs	$ 43	$ 33	$ 85	$ 66