Other Intangible Assets, net and Goodwill - Other Intangible Assets, net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Goodwill And Intangible Assets [Line Items]
Finite-lived intangible assets, Gross	$ 2,823,756		$ 2,323,087
Finite-lived intangible assets, Accumulated Amortization	(705,683)		(658,875)
Total finite-lived intangible assets	2,118,073		1,664,212
Intangible assets, Gross	2,988,031		2,487,515
Total intangible assets	2,282,348		1,828,640
Amortization amounted	49,112	$ 56,106
Trade names
Goodwill And Intangible Assets [Line Items]
Indefinite-lived intangible assets, gross	164,275		164,428
Customer relationships
Goodwill And Intangible Assets [Line Items]
Finite-lived intangible assets, Gross	656,500		280,493
Finite-lived intangible assets, Accumulated Amortization	(182,765)		(180,571)
Total finite-lived intangible assets	473,735		99,922
Databases and content
Goodwill And Intangible Assets [Line Items]
Finite-lived intangible assets, Gross	1,802,169		1,755,323
Finite-lived intangible assets, Accumulated Amortization	(370,220)		(342,385)
Total finite-lived intangible assets	1,431,949		1,412,938
Computer software
Goodwill And Intangible Assets [Line Items]
Finite-lived intangible assets, Gross	330,318		285,701
Finite-lived intangible assets, Accumulated Amortization	(152,114)		(135,919)
Total finite-lived intangible assets	178,204		149,782
Trade names
Goodwill And Intangible Assets [Line Items]
Finite-lived intangible assets, Gross	6,770		1,570
Finite-lived intangible assets, Accumulated Amortization	0		0
Total finite-lived intangible assets	6,770		$ 1,570
Backlog
Goodwill And Intangible Assets [Line Items]
Finite-lived intangible assets, Gross	27,999
Finite-lived intangible assets, Accumulated Amortization	(584)
Total finite-lived intangible assets	$ 27,415