Benefit Obligations (Schedule of Amortization of Accumulated Other Comprehensive Income (Loss), Net Into Net Periodic Benefit Cost) (Details) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	$ 0
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	$ (2)

Amount included in accumulated other comprehensive income (AOCI) related to prior service cost (credit) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

No definition available.

Name:	us-gaap_DefinedBenefitPlanFutureAmortizationOfPriorServiceCostCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration