Employee Benefits Schedule of Net Benefit Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2	$ 2
Interest cost on benefit obligation	4	3	4
Expected return on plan assets	(2)	(2)	(2)
Amortization of prior service cost	1	1	1
Amortization of net actuarial loss	0	1	1
Net periodic benefit cost	5	5	6
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	16	18	15
Interest cost on benefit obligation	33	31	34
Expected return on plan assets	(40)	(40)	(39)
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	14	20	17
Net periodic benefit cost	23	29	27
Non Qualified Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost on benefit obligation	1	1	1
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	1	1	1
Net periodic benefit cost	$ 2	$ 2	$ 2