Benefit Plans (Components of net periodic cost (benefit)) (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 0	$ 4
Interest cost on projected benefit obligation	29	29	85	85
Expected return on plan assets	(41)	(44)	(121)	(131)
Amortization of net actuarial (gain) loss	9	7	28	26
Net periodic (benefit) cost	$ (3)	$ (8)	$ (8)	$ (16)