Goodwill and Other Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	$ 1,167	$ 1,183
Dispositions		(6)
Acquisitions	126
Other	(3)	(10)
Ending balance	1,290	1,167	$ 1,183
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	493	391
Current year amortization	122	98	96
Dispositions		(6)
Reclassifications	0	0
Other (primarily Fx)	(3)	10
Accumulated amortization, ending balance	612	493	391
Net definite-lived intangibles	678	674
Databases and software
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	554	506
Dispositions		(4)
Acquisitions	3
Other	4	52
Ending balance	561	554	506
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	187	132
Current year amortization	52	52
Dispositions		(3)
Reclassifications	1	2
Other (primarily Fx)	0	4
Accumulated amortization, ending balance	240	187	132
Net definite-lived intangibles	321	367
Content
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	139	139
Dispositions		0
Acquisitions	0
Other	0	0
Ending balance	139	139	139
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	101	87
Current year amortization	14	14
Dispositions		0
Reclassifications	0	0
Other (primarily Fx)	0	0
Accumulated amortization, ending balance	115	101	87
Net definite-lived intangibles	24	38
Customer relationships
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	347	330
Dispositions		(2)
Acquisitions	0
Other	(1)	19
Ending balance	346	347	330
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	106	84
Current year amortization	21	22
Dispositions		(2)
Reclassifications		1
Other (primarily Fx)	(1)	1
Accumulated amortization, ending balance	126	106	84
Net definite-lived intangibles	220	241
Tradenames
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	50	45
Dispositions		0
Acquisitions	0
Other	0	5
Ending balance	50	50	45
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	42	36
Current year amortization	3	4
Dispositions		0
Reclassifications	0	1
Other (primarily Fx)	0	1
Accumulated amortization, ending balance	45	42	36
Net definite-lived intangibles	5	8
Other intangibles
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	77	163
Dispositions		0
Acquisitions	123
Other	(6)	(86)
Ending balance	194	77	163
Finite-lived Intangible Assets, Accumulated Amortization [Roll Forward]
Accumulated amortization, beginning balance	57	52
Current year amortization	32	6
Dispositions		(1)
Reclassifications	(1)	(4)
Other (primarily Fx)	(2)	4
Accumulated amortization, ending balance	86	57	$ 52
Net definite-lived intangibles	$ 108	$ 20