Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance			$ 4,636
Other comprehensive income (loss)	$ (65)	$ 50	(27)	$ 221
AOCI, ending balance	6,687		6,687
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance			(2,586)	(2,561)
Other comprehensive income (loss) before reclassifications			60	207
Net losses (gains) reclassified from accumulated other comprehensive loss			(87)	14
Other comprehensive income (loss)			(27)	221
AOCI, ending balance	(2,613)	(2,340)	(2,613)	(2,340)
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance			(1,435)	(1,270)
Other comprehensive income (loss) before reclassifications			602	164
Net losses (gains) reclassified from accumulated other comprehensive loss			0	0
Other comprehensive income (loss)			602	164
AOCI, ending balance	(833)	(1,106)	(833)	(1,106)
Net investment hedging activities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance			140
Other comprehensive income (loss) before reclassifications			(307)
Other comprehensive income (loss)			(307)
AOCI, ending balance	(167)		(167)
Pension and post- employment benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance			(1,513)	(1,378)
Other comprehensive income (loss) before reclassifications			(37)	7
Net losses (gains) reclassified from accumulated other comprehensive loss			58	41
Other comprehensive income (loss)			21	48
AOCI, ending balance	(1,492)	(1,330)	(1,492)	(1,330)
Marketable security activities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance			46	47
Other comprehensive income (loss) before reclassifications			31	23
Net losses (gains) reclassified from accumulated other comprehensive loss			(49)	(4)
Other comprehensive income (loss)			(18)	19
AOCI, ending balance	28	66	28	66
Cash flow hedging activities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI, beginning balance			176	40
Other comprehensive income (loss) before reclassifications			(229)	13
Net losses (gains) reclassified from accumulated other comprehensive loss			(96)	(23)
Other comprehensive income (loss)			(325)	(10)
AOCI, ending balance	$ (149)	$ 30	$ (149)	$ 30