Accumulated Other Comprehensive (Loss) Income (AOCI) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax at beginning of period	$ (557)	$ (590)	$ (553)	$ (761)
OCI	(43)	77	(59)	205
Income taxes	(4)	13	5	48
Cost of Revenue	1,087	1,022	3,323	3,034
Other income (expense), net	(42)	(54)	(140)	(169)
Income taxes	56	(37)	(214)	(145)
Total other comprehensive income, net of tax	(47)	92	(51)	263
Accumulated Other Comprehensive Income (Loss), Net of Tax at end of period	(604)	(498)	(604)	(498)
Reclassification out of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cost of Revenue	0	1	2	12
Other income (expense), net	0	1	1	1
Income taxes	0		0	(3)
Total other comprehensive income, net of tax	(47)	92	(51)	263
Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax at beginning of period	(5)	0	(4)	0
OCI	1	(6)	(1)	(6)
Income taxes	0	2	0	2
Accumulated Other Comprehensive Income (Loss), Net of Tax at end of period	(5)	(3)	(5)	(3)
Marketable Securities | Reclassification out of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cost of Revenue	0	0	0	0
Other income (expense), net	(1)	1	0	1
Income taxes	0		0	0
Total other comprehensive income, net of tax	0	(3)	(1)	(3)
Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax at beginning of period	(132)	(142)	(134)	(132)
OCI	(2)	16	(6)	1
Income taxes	(2)	(4)	1	(1)
Accumulated Other Comprehensive Income (Loss), Net of Tax at end of period	(135)	(128)	(135)	(128)
Pension Plans | Reclassification out of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cost of Revenue	2	2	6	5
Other income (expense), net	0	0	0	0
Income taxes	(1)		(2)	(1)
Total other comprehensive income, net of tax	(3)	14	(1)	4
Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax at beginning of period	45	23	28	24
OCI	8	(7)	32	(17)
Income taxes	(2)	2	(8)	5
Accumulated Other Comprehensive Income (Loss), Net of Tax at end of period	51	17	51	17
Hedges | Reclassification out of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cost of Revenue	(2)	(1)	(4)	7
Other income (expense), net	1	0	1	0
Income taxes	1		2	(2)
Total other comprehensive income, net of tax	6	(6)	23	(7)
Financial Statement Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax at beginning of period	(465)	(471)	(443)	(653)
OCI	(50)	74	(84)	227
Income taxes	0	13	12	42
Accumulated Other Comprehensive Income (Loss), Net of Tax at end of period	(515)	(384)	(515)	(384)
Financial Statement Translation | Reclassification out of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Cost of Revenue	0	0	0	0
Other income (expense), net	0	0	0	0
Income taxes	0		0	0
Total other comprehensive income, net of tax	$ (50)	$ 87	$ (72)	$ 269