Employee Benefits Schedule of Defined Benefit Plan Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair value of plan assets:
Actuarial loss (gain)	$ 5	$ 2
Classification in consolidated balance sheet:
Noncurrent asset	(42)	(38)
Assumptions used:
Defined Benefit Plan, Benefit Obligation, Changes Between Actual and Expected Return on Plan Assets, Gains	1	1
Pension Plans, Defined Benefit [Member]
Benefit obligation:
As of January 1	1,010	905	$ 811
Fair value of plan assets:
Service cost	17	16	19
Interest cost on benefit obligation	31	34	32
Participants’ contributions	0	0
Actuarial loss (gain)	104	88
Benefit payments	(44)	(42)
Defined Benefit Plan, Plan Assets, Administration Expense	(3)	(2)
As of January 1	753	695	546
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(257)	(210)
Net actuarial loss (gain) included in comprehensive income	43	(3)
Other Postretirement Benefits Cost (Reversal of Cost)	1
Defined Benefit Plan, Amortization of Gain (Loss)	(17)	(10)	(17)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	0
Total Amounts included in comprehensive income	27	(13)
Defined Benefit Plan, Accumulated Benefit Obligation	907	813
Actual return on plan assets	105	131
Company contributions	0	62
Classification in consolidated balance sheet:
Noncurrent asset	0	0
Current liability	0	0
Noncurrent liability	(257)	(210)
Amounts included in AOCL:
Net actuarial loss	239	213
Prior service cost	1	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	$ 240	$ 213
Assumptions used:
Discount rate used to calculate benefit obligation	3.43%	4.25%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	3.65%	3.65%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	7.00%	7.00%
Defined Benefit Plan, Benefit Obligation, Changes Between Actual and Expected Return on Plan Assets, Gains	$ 61	$ 94
Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]
Fair value of plan assets:
As of January 1	0	0
Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value of plan assets:
As of January 1	49	49
Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value of plan assets:
As of January 1	0	0
Other Postretirement Benefit Plans [Member]
Benefit obligation:
As of January 1	76	71	72
Fair value of plan assets:
Service cost	2	2	2
Interest cost on benefit obligation	2	3	3
Participants’ contributions	0	2
Actuarial loss (gain)	4	8
Benefit payments	(4)	(6)
Defined Benefit Plan, Plan Assets, Administration Expense	0	0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment	(1)	9
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	0	1
As of January 1	35	34	30
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(41)	(37)
Net actuarial loss (gain) included in comprehensive income	4	5
Other Postretirement Benefits Cost (Reversal of Cost)	0	9
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	1	0	0
Total Amounts included in comprehensive income	5	(4)
Actual return on plan assets	2	5
Company contributions	3	3
Classification in consolidated balance sheet:
Noncurrent asset	0	0
Current liability	0	0
Noncurrent liability	(41)	(37)
Amounts included in AOCL:
Net actuarial loss	5	1
Prior service cost	(8)	(9)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	$ (3)	$ (8)
Assumptions used:
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	4.58%	4.58%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.02%	5.88%
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 3 [Member]
Fair value of plan assets:
As of January 1	$ 0	$ 0
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value of plan assets:
As of January 1	13	13
Other Postretirement Benefit Plans [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value of plan assets:
As of January 1	8	8
Non Qualified Benefit Plans [Member]
Benefit obligation:
As of January 1	28	26	24
Fair value of plan assets:
Service cost	0	0	0
Interest cost on benefit obligation	1	1	1
Participants’ contributions	0	0
Actuarial loss (gain)	3	3
Benefit payments	(2)	(2)
Defined Benefit Plan, Plan Assets, Administration Expense	0	0
As of January 1	19	17	16
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(9)	(9)
Net actuarial loss (gain) included in comprehensive income	3	3
Defined Benefit Plan, Amortization of Gain (Loss)	(1)	(1)	(1)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0	0	$ 0
Total Amounts included in comprehensive income	2	2
Defined Benefit Plan, Accumulated Benefit Obligation	24	26
Actual return on plan assets	1	1
Company contributions	3	2
Classification in consolidated balance sheet:
Noncurrent asset	(19)	(17)
Current liability	(2)	(2)
Noncurrent liability	(26)	(24)
Amounts included in AOCL:
Net actuarial loss	15	13
Prior service cost	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	$ 15	$ 13
Assumptions used:
Discount rate used to calculate benefit obligation	3.43%	3.43%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	4.10%