Employee Benefits - Net Pension Cost (Benefit) for All Funded and Unfunded Plans (Details) - Pension Plans [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Interest cost on PBO	$ 11	$ 10	$ 34	$ 30
Expected return on plan assets	(12)	(13)	(36)	(39)
Amortization of losses	4	4	11	12
Net pension/postretirement benefit cost	$ 3	$ 1	$ 9	$ 3