Shareholders' Equity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	$ (2,106)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(2,405)	$ (2,106)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(185)	(580)
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	(1,962)	(1,353)
Net realized gains (losses)	7	(1)
Other Comprehensive Income (Loss), Tax	(12)	(28)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(190)	(609)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(2,152)	(1,962)
Deferred Gain (Loss) On Hedging Activities [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(191)	(19)
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	61	17
Net realized gains (losses)	100	76
Other Comprehensive Income (Loss), Tax	18	(13)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(73)	44
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(12)	61
Pension Liability Adjustment [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(89)	124
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	(220)	(321)
Net realized gains (losses)	(9)	32
Other Comprehensive Income (Loss), Tax	50	(55)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(48)	101
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(268)	(220)
Unrealized Gain (Loss) On Investments [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	14	(2)
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	15	20
Net realized gains (losses)	(1)	(2)
Other Comprehensive Income (Loss), Tax	(1)	(1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	12	(5)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	27	15
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(451)	(477)
Accumulated other comprehensive income (loss)
Balance of Accumulated Other Comprehensive Income (Loss) at beginning of period	(2,106)	(1,637)
Net realized gains (losses)	97	105
Other Comprehensive Income (Loss), Tax	55	(97)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(299)	(469)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	$ (2,405)	$ (2,106)