Employee Benefit Plans Employee Benefit Plans (Net Periodic Defined Benefit Cost) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit cost			$ 65	$ 60
Defined Benefit Pension Plans | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	9	28	25
Interest cost	20	19	59	59
Expected return on plan assets	(33)	(29)	(99)	(85)
Amortization of prior service cost (credit)	1	1	3	3
Amortization of net loss	18	14	56	40
Net periodic defined benefit cost	15	14	47	42
Defined Benefit Pension Plans | Non-Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1	3	3
Interest cost	2	2	7	7
Amortization of prior service cost (credit)	0	0	(1)	(1)
Amortization of net loss	3	1	8	5
Net periodic defined benefit cost	6	4	17	14
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	1	3	3
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of transition obligations	0	1	0	3
Amortization of net loss	0	0	1	1
Net periodic defined benefit cost	$ 0	$ 1	$ 1	$ 4