Shareholders' Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	$ 12,726	$ 11,659	$ 10,294
Balance at end of period	13,598	12,726	11,659
AOCI Attributable to Parent [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(1,119)	(1,066)	(768)
Balance at end of period	(1,309)	(1,119)	(1,066)
Unrealized (Loss) Gain on Hedges [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(49)	9	16
Other comprehensive (loss) income, net of tax	(108)	(58)	(7)
Balance at end of period	(157)	(49)	9
Defined Benefit Plans [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	1	1	1
Reclassification adjustment	0	0	0
Balance at end of period	1	1	1
Foreign Currency Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(1,071)	(1,076)	(785)
Other comprehensive (loss) income, net of tax	(82)	5	(291)
Balance at end of period	$ (1,153)	$ (1,071)	$ (1,076)