Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 335,257	$ 172,492	$ 212,948
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(18,062)	41,691	(19,773)
Unrealized gain (loss) on derivative instruments	457	(330)	(1,572)
Retirement benefit plan activity	261	(3,153)	0
Comprehensive income	$ 317,913	$ 210,700	$ 191,603