Benefit Plans (Termination, Settlement and Curtailment Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Termination, settlement, and curtailment costs	$ 27
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	23	$ 0
Net loss	9	8
Prior service cost (credit)	2	0
Termination, settlement, and curtailment costs	34	8	$ 0
Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	11
Net loss	0
Prior service cost (credit)	(13)
Termination, settlement, and curtailment costs	$ (2)	$ 0	$ 0