Benefit Plans (Components of net periodic cost (benefit)) (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost on projected benefit obligation	25	24	50	47
Expected return on plan assets	(35)	(40)	(71)	(80)
Amortization of net actuarial (gain) loss	10	9	20	18
Settlement loss	0	1	0	5
Total non-service cost (benefit)	0	(6)	(1)	(10)
Total net periodic pension cost (benefit)	$ 0	$ (6)	$ (1)	$ (10)