Goodwill and Other Intangible Assets - Goodwill and other intangible assets rollforward (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Goodwill
Goodwill, beginning of period	$ 1,234,150
Goodwill, foreign currency translation	(6,448)
Goodwill, end of period	1,227,702
Intangible assets with an indefinite life
Intangible assets with an indefinite life, beginning of period	699,014
Indefinite-lived intangible assets, foreign currency translation	(5,608)
Intangible assets with an indefinite life, end of period	693,406
Intangible assets with a definite life
Intangible assets with a definite life, beginning of period	292,587
Amortization	(10,091)
Identified definite life intangible assets, foreign currency translation	(2,519)
Intangible assets with a definite life, end of period	279,977
Total
Goodwill and other intangible assets, beginning of period	2,225,751
Amortization	(10,091)
Foreign currency translation	(14,575)
Goodwill and other intangible assets, end of period	$ 2,201,085