Accumulated Other Comprehensive (Loss) Income Amount of Income Tax (Expense) Benefit Allocated to Component of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Foreign currency translation, Other comprehensive income (loss), before tax	$ 228,508	$ (20,849)	$ (451,762)
Foreign currency translation, Income tax (expense) benefit	(1,069)	24	38,792
Foreign currency translation, Other comprehensive income (loss), net of tax	227,439	(20,825)	(412,970)
Pension and other postretirement benefits, Other comprehensive (loss) income, before tax	(96)	839	(751)
Pension and other postretirement benefits, Income tax expense	(1)	(5)	(7)
Pension and other postretirement benefits, Other comprehensive (loss) income, net of tax	(97)	834	(758)
Net investment hedge, Other comprehensive (loss) income, before tax	(65,958)	41,209	80,746
Net investment hedge, Income tax benefit (expense)	24,131	(15,076)	(29,885)
Net investment hedge, Other comprehensive (loss) income, net of tax	(41,827)	26,133	50,861
Interest rate swap, Other comprehensive income, before tax	3,336	3,336	3,336
Interest rate swap, Income tax expense	(1,220)	(1,220)	(1,235)
Interest rate swap, Other comprehensive income, net of tax	$ 2,116	$ 2,116	$ 2,101