Accumulated Other Comprehensive Income (AOCI) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	$ (2,242)	$ (2,106)
Other comprehensive income (loss) before reclassifications	114	(43)
Amounts reclassified from AOCI	(3)	3
Other comprehensive income (loss), tax, portion attributable to parent	1	16
Other Comprehensive Income (Loss), Net of Tax	112	(24)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(2,130)	(2,130)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	(2,051)	(1,962)
Other comprehensive income (loss) before reclassifications	94	16
Amounts reclassified from AOCI	0	(1)
Other comprehensive income (loss), tax, portion attributable to parent	7	(3)
Other Comprehensive Income (Loss), Net of Tax	101	12
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(1,950)	(1,950)
Deferred Gain (Loss) On Hedging Activities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	(4)	61
Other comprehensive income (loss) before reclassifications	14	(73)
Amounts reclassified from AOCI	0	10
Other comprehensive income (loss), tax, portion attributable to parent	(7)	5
Other Comprehensive Income (Loss), Net of Tax	7	(58)
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	3	3
Pension Liability Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	(200)	(220)
Other comprehensive income (loss) before reclassifications	(1)	9
Amounts reclassified from AOCI	(3)	(6)
Other comprehensive income (loss), tax, portion attributable to parent	2	15
Other Comprehensive Income (Loss), Net of Tax	(2)	18
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	(202)	(202)
Unrealized Gain (Loss) On Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance of Accumulated Other Comprehensive Income (Loss) at Beginning of Period	13	15
Other comprehensive income (loss) before reclassifications	7	5
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss), tax, portion attributable to parent	(1)	(1)
Other Comprehensive Income (Loss), Net of Tax	6	4
Balance of Accumulated Other Comprehensive Income (Loss) at End of period	$ 19	$ 19