Goodwill and Other Intangible Assets - Analysis of Goodwill and intangible assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, beginning of year	$ 1,213,524	$ 1,213,630	$ 415,936
Goodwill, acquired during period		14,084	807,381
Foreign currency translation, goodwill	20,626	(14,190)	(9,687)
Goodwill, end of year	1,234,150	1,213,524	1,213,630
Intangible assets with an indefinite life, beginning of year	682,779	682,859	15,366
Indefinite-lived Intangible Assets Acquired		8,000	673,000
Foreign currency translation, indefinite-lived intangible assets	16,235	(8,080)	(5,507)
Intangible assets with an indefinite life, end of year	699,014	682,779	682,859
Intangible assets with a definite life, beginning of year	307,350	313,777	16,650
Finite-lived Intangible Assets Acquired		28,948	315,000
Amortization	(21,834)	(22,422)	(15,517)
Foreign currency translation, intangible assets with an definite life	7,071	(12,953)	(2,356)
Intangible assets with a definite life, end of year	292,587	307,350	313,777
Goodwill and other intangible assets, beginning of year	2,203,653	2,210,266	447,952
Additions		51,032	1,795,381
Foreign currency translation, intangible assets including goodwill	43,932	(35,223)	(17,550)
Goodwill and other intangible assets, end of year	$ 2,225,751	$ 2,203,653	$ 2,210,266