Employee Benefit Plans Employee Benefit Plans (Net Periodic Defined Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Net periodic defined benefit cost			$ 11	$ 34
Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8	$ 9	24	27
Interest cost	23	22	69	66
Expected return on plan assets	(39)	(40)	(120)	(120)
Amortization of prior service cost (credit)	1	1	3	3
Amortization of net loss	7	15	23	44
Net periodic defined benefit cost	0	7	(1)	20
Non-Qualified Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	1	2	3
Interest cost	3	2	8	7
Amortization of prior service cost (credit)	(1)	(1)	(3)	(3)
Amortization of net loss	2	3	5	8
Net periodic defined benefit cost	4	5	12	15
Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0	1	2	2
Expected return on plan assets	(1)	(1)	(3)	(3)
Amortization of net loss	1	0	1	1
Net periodic defined benefit cost	$ 0	$ 0	$ 0	$ 0