Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss	$ (2,749)	$ (2,332)	$ (2,702)	$ (2,116)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(85)	(387)
Other Comprehensive Income (Loss), Before Reclassifications, Tax	22	102
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	16	69
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(47)	(216)
Translation Adjustments Other Than Translation Of Balance Sheet Tax Benefit Expense	(46)	20
Pension and other postretirement benefit adjustments, tax cost	(20)	31
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	(3)	1
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss	(1,414)	(922)	(1,332)	(628)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(85)	(387)
Other Comprehensive Income (Loss), Before Reclassifications, Tax	3	93
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(82)	(294)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss	(1,336)	(1,418)	(1,379)	(1,492)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Before Reclassifications, Tax	17	32
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	26	42
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	43	74
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive loss	1	8	$ 9	$ 4
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Before Reclassifications, Tax	2	(23)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(10)	27
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ (8)	$ 4