Risk Management Risk Management Reporting of Amounts Reclassified out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	$ 42	$ 179	$ 219	$ 327
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Before Reclassifications, Portion Attributable to Parent	65	(170)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(342)	(229)	(358)	(236)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(557)	(328)	(461)	(17)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	16	7
Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax Portion Attributable To Parent	(19)	44
OCI, before Reclassifications, Net of Tax, Attributable to Parent	62	(119)
Other Comprehensive Income Reclassification Adjustment On Derivatives Included In Net Income Net Of Tax Portion Attributable To Parent	(158)	(192)
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	(257)	(278)	$ (322)	$ (108)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0	0
Other Comprehensive Income Loss Reclassification Adjustment From AOCI Pension And Other Postretiremen tBenefit Plans Net Of Tax Portion Attributable To Parent	0	0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	(158)	(192)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent	(177)	(148)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment and Impact of Merger Transactions, Net of Tax, Portion Attributable to Parent	65	(170)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	16	7
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ (96)	$ (311)