Shareholders' Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	$ 12,385	$ 10,976	$ 11,659	$ 10,294
Other comprehensive (loss) income, net of tax	(176)	(34)	(144)	(202)
Balance at end of period	12,688	11,852	12,688	11,852
AOCI Attributable to Parent [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(1,034)	(936)	(1,066)	(768)
Balance at end of period	(1,210)	(970)	(1,210)	(970)
Unrealized Gain (Loss) on Hedges [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(24)	34	9	16
Other comprehensive (loss) income, net of tax	(12)	1	(45)	19
Balance at end of period	(36)	35	(36)	35
Defined Benefit Plans [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	1	1	1	1
Other comprehensive (loss) income, net of tax	0	0	0	0
Balance at end of period	1	1	1	1
Foreign Currency Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(1,011)	(971)	(1,076)	(785)
Other comprehensive (loss) income, net of tax	(164)	(35)	(99)	(221)
Balance at end of period	$ (1,175)	$ (1,006)	$ (1,175)	$ (1,006)