Benefit Plans (Components of net periodic cost (benefit)) (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	$ 20	$ 25	$ 40	$ 50
Expected return on plan assets	(39)	(35)	(78)	(71)
Amortization of net actuarial (gain) loss	11	10	22	20
Settlement loss	1	0	2	0
Total net periodic pension cost (benefit)	$ (7)	$ 0	$ (14)	$ (1)