Net Investment Hedge Net Investment Hedge (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative translation adjustment	$ 27,802	$ (65,046)	$ 18,687
Senior Subordinated Notes
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative translation adjustment	$ 87,500	$ (56,200)