Employee Benefits - Net Pension Cost (Benefit) for All Funded and Unfunded Plans (Details) - Pension Plans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Interest cost on PBO	$ 6	$ 8	$ 12	$ 17
Expected return on plan assets	(7)	(9)	(14)	(19)
Amortization of losses	4	4	9	8
Settlement loss	0	4	0	8
Net pension cost	$ 3	$ 7	$ 7	$ 14