Benefit Plans (Components of net periodic cost (benefit)) (Details) - Pension Benefits - 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]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost on projected benefit obligation	25	23	75	70
Expected return on plan assets	(36)	(40)	(107)	(120)
Amortization of net actuarial (gain) loss	10	10	30	28
Settlement loss	0	0	0	5
Total non-service cost (benefit)	(1)	(7)	(2)	(17)
Total net periodic pension cost (benefit)	$ (1)	$ (7)	$ (2)	$ (17)