Benefit Plans (Components of net periodic cost (benefit)) (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0
Interest cost on projected benefit obligation	25	23
Expected return on plan assets	(36)	(40)
Amortization of net actuarial (gain) loss	10	9
Settlement loss	0	4
Total non-service cost (benefit)	(1)	(4)
Total net periodic pension cost (benefit)	$ (1)	$ (4)