Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (8,446)	$ 5,097	$ 4,636
Other comprehensive income (loss)	(1,116)	247	(141)
Ending balance	(8,172)	(8,446)	5,097
Currency translation adjustment reclassification from AOCI tax impact		0
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(2,480)	(2,727)	(2,586)
Other comprehensive income (loss) before reclassifications	(1,023)	(27)	(344)
Net losses reclassified from accumulated other comprehensive loss	(93)	274	203
Other comprehensive income (loss)	(1,116)	247	(141)
Ending balance	(3,596)	(2,480)	(2,727)
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(830)	(439)	(1,435)
Other comprehensive income (loss) before reclassifications	(98)	(391)	680
Net losses reclassified from accumulated other comprehensive loss	0		316
Other comprehensive income (loss)	(98)	(391)	996
Ending balance	(928)	(830)	(439)
Net investment hedging activities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(65)	(203)	140
Other comprehensive income (loss) before reclassifications	95	138	(343)
Net losses reclassified from accumulated other comprehensive loss	(21)	0	0
Other comprehensive income (loss)	74	138	(343)
Ending balance	9	(65)	(203)
Pension and post-employment benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1,722)	(1,919)	(1,513)
Other comprehensive income (loss) before reclassifications	(1,330)	84	(480)
Net losses reclassified from accumulated other comprehensive loss	87	113	74
Other comprehensive income (loss)	(1,243)	197	(406)
Ending balance	(2,965)	(1,722)	(1,919)
Marketable security activities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(10)	0	46
Other comprehensive income (loss) before reclassifications	12	(14)	29
Net losses reclassified from accumulated other comprehensive loss	(2)	4	(75)
Other comprehensive income (loss)	10	(10)	(46)
Ending balance	0	(10)	0
Cash flow hedging activities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	147	(166)	176
Other comprehensive income (loss) before reclassifications	298	156	(230)
Net losses reclassified from accumulated other comprehensive loss	(157)	157	(112)
Other comprehensive income (loss)	141	313	(342)
Ending balance	$ 288	$ 147	$ (166)