Employee Benefits - Net Pension Cost (Benefit) for All Funded and Unfunded Plans (Details) - Pension Plans - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest cost on PBO	$ 9	$ 11	$ 26	$ 34
Expected return on plan assets	(10)	(12)	(29)	(36)
Amortization of losses	5	4	13	11
Settlement loss	0	0	8	0
Net pension cost	$ 4	$ 3	$ 18	$ 9