Benefit Plans (Components of net periodic cost (benefit)) (Details) - Pension Benefits - 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 projected benefit obligation	$ 20	$ 25	$ 60	$ 75
Expected return on plan assets	(38)	(36)	(116)	(107)
Amortization of net actuarial (gain) loss	11	10	33	30
Settlement loss	0	0	2	0
Total net periodic pension cost (benefit)	$ (7)	$ (1)	$ (21)	$ (2)