Employee Benefits Schedule of Defined Benefit Plan Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Debt Securities— Domestic Government Other Postretirement Benefit Plan Assets	$ 5	$ 5
Fair value of plan assets:
As of January 1		546
Classification in consolidated balance sheet:
Noncurrent asset	(38)	(36)
Noncurrent liability	(247)	(307)
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Debt Securities— Domestic Government Other Postretirement Benefit Plan Assets	0	0
Fair value of plan assets:
As of January 1	0	0
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Debt Securities— Domestic Government Other Postretirement Benefit Plan Assets	0	0
Fair value of plan assets:
As of January 1	49	67
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Debt Securities— Domestic Government Other Postretirement Benefit Plan Assets	5	5
Fair value of plan assets:
As of January 1	0	0
Pension Plans, Defined Benefit [Member]
Benefit obligation:
As of January 1	905	811	$ 869
Fair value of plan assets:
Service cost	16	19	17
Interest cost on benefit obligation	34	32	33
Participants’ contributions	0	0
Actuarial loss (gain)	88	(67)
Benefit payments	(42)	(39)
Defined Benefit Plan, Plan Assets, Administration Expense	(2)	(3)
As of January 1	695	546	629
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(210)	(265)
Net actuarial loss (gain) included in comprehensive income	(3)	25
Defined Benefit Plan, Amortization of Gain (Loss)	(10)	(17)	(13)
Total Amounts included in comprehensive income	(13)	8
Defined Benefit Plan, Accumulated Benefit Obligation	813	734
Actual return on plan assets	131	(50)
Company contributions	62	9
Classification in consolidated balance sheet:
Noncurrent asset	0	0
Current liability	0	0
Noncurrent liability	(210)	(265)
Amounts included in AOCL:
Net actuarial loss	213	226
Prior service cost	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	$ 213	$ 226
Assumptions used:
Discount rate used to calculate benefit obligation	4.25%	3.65%
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%
Other Postretirement Benefit Plans [Member]
Benefit obligation:
As of January 1	$ 71	$ 72	78
Fair value of plan assets:
Service cost	2	2	2
Interest cost on benefit obligation	3	3	3
Participants’ contributions	2	2
Actuarial loss (gain)	8	(7)
Benefit payments	(6)	(6)
Defined Benefit Plan, Plan Assets, Administration Expense	0	0
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment	9
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	1
As of January 1	34	30	33
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(37)	(42)
Net actuarial loss (gain) included in comprehensive income	5	(4)
Other Postretirement Benefits Cost (Reversal of Cost)	9
Defined Benefit Plan, Amortization of Gain (Loss)	0	0	0
Total Amounts included in comprehensive income	(4)	(4)
Actual return on plan assets	5	(2)
Company contributions	3	3
Classification in consolidated balance sheet:
Noncurrent asset	0	0
Current liability	0	0
Noncurrent liability	(37)	(42)
Amounts included in AOCL:
Net actuarial loss	1	(4)
Prior service cost	(9)	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	$ (8)	$ (4)
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	5.88%	6.20%
Non Qualified Benefit Plans [Member]
Benefit obligation:
As of January 1	$ 26	$ 24	27
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	(1)
Benefit payments	(2)	(3)
Defined Benefit Plan, Plan Assets, Administration Expense	0	0
As of January 1	17	16	17
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(9)	(8)
Net actuarial loss (gain) included in comprehensive income	3	(1)
Defined Benefit Plan, Amortization of Gain (Loss)	(1)	(1)	$ (1)
Total Amounts included in comprehensive income	2	(2)
Defined Benefit Plan, Accumulated Benefit Obligation	26	24
Actual return on plan assets	1	(1)
Company contributions	2	3
Classification in consolidated balance sheet:
Noncurrent asset	(17)	(16)
Current liability	(2)	(2)
Noncurrent liability	(24)	(22)
Amounts included in AOCL:
Net actuarial loss	13	11
Prior service cost	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	$ 13	$ 11
Assumptions used:
Discount rate used to calculate benefit obligation	3.43%	3.65%