Goodwill and Intangible Assets - Carrying Amounts of Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance	$ 1,482,982
Write-off of fully amortized intangible assets	(228)
Reclassified as held-for-sale	7,771
Foreign currency translation impact	15,789
Gross cost, ending balance	1,490,772
Accumulated amortization	(243,001)		$ (190,960)
Finite-lived intangible assets, net	1,247,771		1,292,022
Amortization of intangibles	51,646	$ 6,290
Customer Relationships
Finite-lived Intangible Assets [Roll Forward]
Gross cost, beginning balance	1,200,316
Write-off of fully amortized intangible assets	0
Reclassified as held-for-sale	7,170
Foreign currency translation impact	15,218
Gross cost, ending balance	1,208,364
Accumulated amortization	(119,075)		(92,983)
Finite-lived intangible assets, net	$ 1,089,289		1,107,333
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	$ 123,424
Write-off of fully amortized intangible assets	0
Reclassified as held-for-sale	321
Foreign currency translation impact	491
Gross cost, ending balance	123,594
Accumulated amortization	(32,410)		(26,344)
Finite-lived intangible assets, net	$ 91,184		97,080
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	$ 104,313
Write-off of fully amortized intangible assets	(228)
Reclassified as held-for-sale	241
Foreign currency translation impact	251
Gross cost, ending balance	104,095
Accumulated amortization	(63,778)		(47,475)
Finite-lived intangible assets, net	$ 40,317		56,838
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	$ 54,929
Write-off of fully amortized intangible assets	0
Reclassified as held-for-sale	39
Foreign currency translation impact	(171)
Gross cost, ending balance	54,719
Accumulated amortization	(27,738)		(24,158)
Finite-lived intangible assets, net	$ 26,981		$ 30,771
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	5 years