Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	$ 1,183	$ 1,133
Acquisitions		98
Dispositions	(6)	(10)
Impairment	(24)	(24)
Reclassifications		0
Other (primarily Fx)	(10)	(14)
Ending balance	1,167	1,183	$ 1,133
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	391	324
Current year amortization	98	96	67
Dispositions	(6)	(7)
Impairment		(12)
Reclassifications	0	0
Other (primarily Fx)	10	(10)
Accumulated amortization, ending balance	493	391	324
Net definite-lived intangibles	674	792
Databases and software
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	506	510
Acquisitions		0
Dispositions	(4)	0
Impairment		(2)
Reclassifications		0
Other (primarily Fx)	52	(2)
Ending balance	554	506	510
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	132	88
Current year amortization	52	47
Dispositions	(3)	0
Impairment		(2)
Reclassifications	2	2
Other (primarily Fx)	4	(3)
Accumulated amortization, ending balance	187	132	88
Net definite-lived intangibles	367	374
Content
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	139	139
Acquisitions		0
Dispositions	0	0
Impairment		0
Reclassifications		0
Other (primarily Fx)	0	0
Ending balance	139	139	139
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	87	73
Current year amortization	14	14
Dispositions	0	0
Impairment		0
Reclassifications	0	0
Other (primarily Fx)	0	0
Accumulated amortization, ending balance	101	87	73
Net definite-lived intangibles	38	52
Customer relationships
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	330	168
Acquisitions		0
Dispositions	(2)	0
Impairment		0
Reclassifications		165
Other (primarily Fx)	19	(3)
Ending balance	347	330	168
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	84	60
Current year amortization	22	21
Dispositions	(2)	0
Impairment		0
Reclassifications	1	5
Other (primarily Fx)	1	(2)
Accumulated amortization, ending balance	106	84	60
Net definite-lived intangibles	241	246
Tradenames
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	45	47
Acquisitions		0
Dispositions	0	(2)
Impairment		0
Reclassifications		1
Other (primarily Fx)	5	(1)
Ending balance	50	45	47
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	36	36
Current year amortization	4	2
Dispositions	0	(1)
Impairment		0
Reclassifications	1	0
Other (primarily Fx)	1	(1)
Accumulated amortization, ending balance	42	36	36
Net definite-lived intangibles	8	9
Other intangibles
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	163	269
Acquisitions		98
Dispositions	0	(8)
Impairment		(22)
Reclassifications		(166)
Other (primarily Fx)	(86)	(8)
Ending balance	77	163	269
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	52	67
Current year amortization	6	12
Dispositions	(1)	(6)
Impairment		(10)
Reclassifications	(4)	(7)
Other (primarily Fx)	4	(4)
Accumulated amortization, ending balance	57	52	$ 67
Net definite-lived intangibles	$ 20	$ 111