Goodwill and Intangible Assets - Carrying Amounts of Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance			$ 1,392,861
Intangible assets fully amortized			(104,580)
Foreign currency translation impact			(10,221)
Gross cost, ending balance	$ 1,278,060		1,278,060
Accumulated amortization	(341,747)		(341,747)		$ (350,296)
Finite-lived intangible assets, net	936,313		936,313		1,042,565
Amortization of intangibles	31,694	$ 50,852	97,541	$ 152,625
Customer Relationships
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance			1,131,656
Intangible assets fully amortized			0
Foreign currency translation impact			(9,810)
Gross cost, ending balance	1,121,846		1,121,846
Accumulated amortization	(255,139)		(255,139)		(184,918)
Finite-lived intangible assets, net	866,707		$ 866,707		946,738
Customer Relationships | Minimum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life			4 years
Customer Relationships | Maximum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life			13 years
Software
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance			$ 110,701
Intangible assets fully amortized			0
Foreign currency translation impact			(303)
Gross cost, ending balance	110,398		110,398
Accumulated amortization	(55,609)		(55,609)		(38,901)
Finite-lived intangible assets, net	54,789		$ 54,789		71,800
Software | Minimum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life			3 years
Software | Maximum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life			7 years
Content
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance			$ 98,842
Intangible assets fully amortized			(85,900)
Foreign currency translation impact			(2)
Gross cost, ending balance	12,940		12,940
Accumulated amortization	(9,973)		(9,973)		(92,717)
Finite-lived intangible assets, net	2,967		$ 2,967		6,125
Content | Minimum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life			1 year 6 months
Content | Maximum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life			5 years
Other
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance			$ 51,662
Intangible assets fully amortized			(18,680)
Foreign currency translation impact			(106)
Gross cost, ending balance	32,876		32,876
Accumulated amortization	(21,026)		(21,026)		(33,760)
Finite-lived intangible assets, net	$ 11,850		$ 11,850		$ 17,902
Other | Minimum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life			2 years
Other | Maximum
Finite-lived Intangible Assets [Roll Forward]
Finite-lived intangible assets useful life			11 years