Shareholders' Equity - Components Of Accumulated OCI (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Cumulative foreign currency translation adjustment	$ (62,689)	$ (78,953)
Unrealized loss on hedges, net of tax	(7,507)	(18,021)
Unrealized gain on note receivable, net of tax	409	0
Accumulated other comprehensive loss	(69,787)	(96,974)
Deferred income taxes	$ 4,000	$ 9,700