Employee Benefits Schedule of Net Benefit Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2	$ 2
Interest cost on benefit obligation	3	3	4
Expected return on plan assets	(1)	(2)	(2)
Amortization of prior service cost	0	0	1
Amortization of net actuarial loss	0	0	0
Net periodic benefit cost	4	3	5
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	19	17	16
Interest cost on benefit obligation	32	33	33
Expected return on plan assets	(42)	(42)	(40)
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	17	13	14
Net periodic benefit cost	26	21	23
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