Shareholders' Equity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	$ (2,405)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(2,604)	$ (2,405)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	29	(220)
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), before Reclassification and Tax	(398)	35
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	(2,152)	(1,962)
Net realized gains (losses)	0	7
Other Comprehensive Income (Loss), Tax	97	(12)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(272)	(190)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(2,424)	(2,152)
Deferred Gain (Loss) On Hedging Activities [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	209	(191)
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	(12)	61
Net realized gains (losses)	45	100
Other Comprehensive Income (Loss), Tax	(57)	18
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	197	(73)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	185	(12)
Pension Liability Adjustment [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(120)	(89)
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	(268)	(220)
Net realized gains (losses)	7	(9)
Other Comprehensive Income (Loss), Tax	16	50
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(97)	(48)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(365)	(268)
Unrealized Gain (Loss) On Investments [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(27)	14
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	27	15
Net realized gains (losses)	0	(1)
Other Comprehensive Income (Loss), Tax	0	(1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(27)	12
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	0	27
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	91	(486)
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), before Reclassification and Tax	(398)	35
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	(2,405)	(2,106)
Net realized gains (losses)	52	97
Other Comprehensive Income (Loss), Tax	56	55
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(199)	(299)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	$ (2,604)	$ (2,405)