Goodwill and Other Intangible Assets - Goodwill and other intangible assets rollforward (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Goodwill
Goodwill, beginning of period	$ 1,234,150
Goodwill, foreign currency translation	4,850
Goodwill, end of period	1,239,000
Intangible assets with an indefinite life
Intangible assets with an indefinite life, beginning of period	699,014
Indefinite-lived intangible assets, foreign currency translation	2,916
Intangible assets with an indefinite life, end of period	701,930
Intangible assets with a definite life
Intangible assets with a definite life, beginning of period	292,587
Amortization	(4,944)
Identified definite life intangible assets, foreign currency translation	1,933
Intangible assets with a definite life, end of period	289,576
Total
Goodwill and other intangible assets, beginning of period	2,225,751
Amortization	(4,944)
Foreign currency translation	9,699
Goodwill and other intangible assets, end of period	$ 2,230,506