Goodwill and Intangible Assets - Carrying Amounts of Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite-lived Intangible Assets [Roll Forward]
Gross cost	$ 1,392,861	$ 1,482,982
Additions due to acquisitions	5,250
Intangible assets fully amortized	(107,258)	(15,998)
Divestitures		(46,129)
Foreign currency translation impact and other	10,267	(27,994)
Gross cost	1,301,120	1,392,861
Accumulated amortization	(376,033)	(350,296)
Finite-lived intangible assets, net	925,087	1,042,565
Customer Relationships
Finite-lived Intangible Assets [Roll Forward]
Gross cost	1,131,656	1,200,316
Additions due to acquisitions	3,600
Intangible assets fully amortized	0	(303)
Divestitures		(45,175)
Foreign currency translation impact and other	9,853	(23,182)
Gross cost	1,145,109	1,131,656
Accumulated amortization	(283,369)	(184,918)
Finite-lived intangible assets, net	$ 861,740	946,738
Customer Relationships | Minimum
Finite-lived Intangible Assets [Roll Forward]
Remaining amortization period	4 years
Customer Relationships | Maximum
Finite-lived Intangible Assets [Roll Forward]
Remaining amortization period	13 years
Software
Finite-lived Intangible Assets [Roll Forward]
Gross cost	$ 110,701	123,424
Additions due to acquisitions	0
Intangible assets fully amortized	0	(11,715)
Divestitures		(321)
Foreign currency translation impact and other	332	(687)
Gross cost	111,033	110,701
Accumulated amortization	(61,564)	(38,901)
Finite-lived intangible assets, net	$ 49,469	71,800
Software | Minimum
Finite-lived Intangible Assets [Roll Forward]
Remaining amortization period	3 years
Software | Maximum
Finite-lived Intangible Assets [Roll Forward]
Remaining amortization period	7 years
Content
Finite-lived Intangible Assets [Roll Forward]
Gross cost	$ 98,842	104,313
Additions due to acquisitions	1,200
Intangible assets fully amortized	(85,900)	(669)
Divestitures		(473)
Foreign currency translation impact and other	(2)	(4,329)
Gross cost	14,140	98,842
Accumulated amortization	(11,225)	(92,717)
Finite-lived intangible assets, net	$ 2,915	6,125
Content | Minimum
Finite-lived Intangible Assets [Roll Forward]
Remaining amortization period	1 year 6 months
Content | Maximum
Finite-lived Intangible Assets [Roll Forward]
Remaining amortization period	4 years
Other
Finite-lived Intangible Assets [Roll Forward]
Gross cost	$ 51,662	54,929
Additions due to acquisitions	450
Intangible assets fully amortized	(21,358)	(3,311)
Divestitures		(160)
Foreign currency translation impact and other	84	204
Gross cost	30,838	51,662
Accumulated amortization	(19,875)	(33,760)
Finite-lived intangible assets, net	$ 10,963	$ 17,902
Other | Minimum
Finite-lived Intangible Assets [Roll Forward]
Remaining amortization period	2 years
Other | Maximum
Finite-lived Intangible Assets [Roll Forward]
Remaining amortization period	11 years