Employee Benefit Plans (Net Periodic Defined Benefit Cost) (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Qualified Defined Benefit Pension Plan [Member]
Service cost	$ 8	$ 8	$ 16	$ 15
Interest cost	19	19	38	36
Expected return on plan assets	(29)	(28)	(58)	(57)
Amortization of unrecognized prior service cost	1	2	2	4
Amortization of unrecognized net loss	9	4	18	8
Net periodic benefit cost	8	5	16	6
Non-Qualified Defined Benefit Pension Plan [Member]
Service cost	1	1	2	2
Interest cost	3	2	5	4
Amortization of unrecognized prior service cost	(1)	(1)	(1)	(1)
Amortization of unrecognized net loss	1	1	2	2
Net periodic benefit cost	4	3	8	7
Postretirement Benefit Plan [Member]
Interest cost	1	1	2	2
Expected return on plan assets	(1)	(1)	(2)	(2)
Amortization of unrecognized transition obligation	1	1	2	2
Amortization of unrecognized net loss	1	1	1	1
Net periodic benefit cost	$ 2	$ 2	$ 3	$ 3