Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Effective income tax rate			22.50%	24.00%
Other Tax Expense (Benefit)			$ 14	$ 3
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 3	$ 2	5	4
Interest cost	5	7	10	13
Amortization of actuarial losses	4	2	8	4
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	(15)	(15)	(30)	(29)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(3)	(4)	(7)	(8)
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	6	5	12	11
Interest cost	21	27	43	53
Amortization of actuarial losses	18	16	36	31
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 10	$ 13	$ 20	$ 25