Postretirement benefits Schedule of amounts in AOCI to be recognized in next fiscal year (Details) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Pension Plan [Member] \| Non-US [Member]
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract]
Future Amortization of (Gain) Loss	$ 3
Other Postretirement Benefit Plan [Member] \| UNITED STATES
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract]
Future Amortization of Prior Service (Cost) Credit	$ 92

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