Employee Benefits Schedule of Net Benefit Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2	$ 2	$ 2
Interest cost on benefit obligation	2	3	3
Expected return on plan assets	(2)	(2)	(1)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(1)	0	0
Amortization of net actuarial loss	0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	0	(2)	0
Net periodic benefit cost	1	1	4
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	17	16	19
Interest cost on benefit obligation	31	34	32
Expected return on plan assets	(44)	(40)	(42)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0
Amortization of net actuarial loss	17	10	17
Net periodic benefit cost	21	20	26
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
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0
Amortization of net actuarial loss	1	1	1
Net periodic benefit cost	$ 2	$ 2	$ 2