Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance			$ (336)				$ (336)
Cumulative effect of adoption									$ (3)
Foreign currency translation adjustment	$ (20)			$ (9)			(9)	$ (61)
Changes in postretirement benefit plans	(11)			0			(11)	0
Other non-operating (expense) income, net	(7)			4			(2)	9
Ending balance	(364)						(364)
Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(327)	$ (316)	(336)	(294)	$ (207)	$ (210)	(336)	(210)
Cumulative effect of adoption									(17)
Foreign currency translation adjustment	(20)	(18)	29	(7)	(60)	8
Foreign currency gain reclassified into gain on sale of businesses	(13)	3	(4)	3	(19)	11
Changes in postretirement benefit plans	(11)					1
Other non-operating (expense) income, net					3
Income tax expense on amortization of postretirement benefit plan items			(1)		(1)	(1)
Unrealized loss on derivative hedge agreements	(5)		(9)		(9)
Income tax benefit on unrealized loss on derivative hedge agreements			1
Ending balance	(364)	(327)	(316)	(293)	(294)	(207)	(364)	(293)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(111)	(96)	(121)	(86)	(7)	(15)	(121)	(15)
Cumulative effect of adoption									(11)
Foreign currency translation adjustment	(20)	(18)	29	(7)	(60)	8
Foreign currency gain reclassified into gain on sale of businesses	(13)	3	(4)	3	(19)	11
Ending balance	(144)	(111)	(96)	(90)	(86)	(7)	(144)	(90)
Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(211)	(213)	(214)	(200)	(202)	(198)	(214)	(198)
Cumulative effect of adoption									$ (6)
Changes in postretirement benefit plans	(11)					1
Other non-operating (expense) income, net					3
Income tax expense on amortization of postretirement benefit plan items			(1)		(1)	(1)
Ending balance	(213)	(211)	(213)	(198)	(200)	(202)	(213)	(198)
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(5)	(7)	(1)	(8)	2	3	(1)	3
Unrealized loss on derivative hedge agreements	(5)		(9)		(9)
Income tax benefit on unrealized loss on derivative hedge agreements			1
Ending balance	(7)	(5)	(7)	(5)	(8)	2	$ (7)	$ (5)
Other non-operating income | Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of prior service cost and net actuarial loss on postretirement benefit plans into other non-operating income (expense), net	1	2	2	2	0	2
Settlement charge released into other non-operating income (expense), net	8
Other non-operating income | Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Amortization of prior service cost and net actuarial loss on postretirement benefit plans into other non-operating income (expense), net	1	2	2	2	0	2
Settlement charge released into other non-operating income (expense), net	8
Revenue | Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification of unrealized gain (loss) on foreign exchange agreements	2	1	1	1	(1)	(1)
Revenue | Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification of unrealized gain (loss) on foreign exchange agreements	2	1	1	1	$ (1)	$ (1)
Cost of Revenue | Total
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification of unrealized gain (loss) on foreign exchange agreements	1	1	1	2
Cost of Revenue | Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Reclassification of unrealized gain (loss) on foreign exchange agreements	$ 1	$ 1	$ 1	$ 2