Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to Parent, Net of Tax
Beginning balance	$ (7,826)	$ 3,553	$ (8,446)	$ 5,097
Other comprehensive income (loss)	25	(9)	(11)	88
Ending balance	(8,566)	(3,375)	(8,566)	(3,375)
Accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax
Beginning balance	(2,516)	(2,630)	(2,480)	(2,727)
Other comprehensive income (loss) before reclassifications			22	(62)
Net losses (gains) reclassified from accumulated other comprehensive loss			(33)	150
Other comprehensive income (loss)	25	(9)	(11)	88
Ending balance	(2,491)	(2,639)	(2,491)	(2,639)
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax
Beginning balance			(830)	(439)
Other comprehensive income (loss) before reclassifications			(32)	(280)
Net losses (gains) reclassified from accumulated other comprehensive loss			0	0
Other comprehensive income (loss)			(32)	(280)
Ending balance	(862)	(719)	(862)	(719)
Net investment hedging activities
AOCI Attributable to Parent, Net of Tax
Beginning balance			(65)	(203)
Other comprehensive income (loss) before reclassifications			35	105
Net losses (gains) reclassified from accumulated other comprehensive loss			(7)	0
Other comprehensive income (loss)			28	105
Ending balance	(37)	(98)	(37)	(98)
Pension and post-employment benefits
AOCI Attributable to Parent, Net of Tax
Beginning balance			(1,722)	(1,919)
Other comprehensive income (loss) before reclassifications			2	9
Net losses (gains) reclassified from accumulated other comprehensive loss			43	62
Other comprehensive income (loss)			45	71
Ending balance	(1,677)	(1,848)	(1,677)	(1,848)
Marketable security activities
AOCI Attributable to Parent, Net of Tax
Beginning balance			(10)	0
Other comprehensive income (loss) before reclassifications			10	(6)
Net losses (gains) reclassified from accumulated other comprehensive loss			1	4
Other comprehensive income (loss)			11	(2)
Ending balance	1	(2)	1	(2)
Cash flow hedging activities
AOCI Attributable to Parent, Net of Tax
Beginning balance			147	(166)
Other comprehensive income (loss) before reclassifications			7	110
Net losses (gains) reclassified from accumulated other comprehensive loss			(70)	84
Other comprehensive income (loss)			(63)	194
Ending balance	$ 84	$ 28	$ 84	$ 28