Shareholders' Equity Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Before-tax amount [Abstract]
Foreign currency translation adjustment	$ (576)	$ 14,169	$ (18,554)	$ 49,755
Foreign currency translation adjustment reclassified into net income	0	1,089	0	1,089
Net unrealized gain (loss) on derivative instruments designated as cash flow hedges	712	57	5,216	(480)
Net hedging (gain) loss reclassified into net income	175	148	(2,198)	785
Net defined benefit plan loss reclassified to net income	399	447	1,228	1,271
Total other comprehensive income (loss), before tax	710	15,910	(14,308)	52,420
Tax (provision) benefit [Abstract]
Foreign currency translation adjustment	(102)	(328)	16	(451)
Net unrealized gain (loss) on derivative instruments designated as cash flow hedges	(20)	(22)	(446)	185
Net hedging (gain) loss reclassified into net income	41	(57)	(9)	(303)
Net defined benefit plan loss reclassified to net income	(7)	(37)	(21)	(267)
Total other comprehensive income (loss) tax benefit	(88)	(444)	(460)	(836)
Net-of-tax amount [Abstract]
Foreign currency translation adjustment	(678)	13,841	(18,538)	49,304
Foreign currency translation adjustment reclassified into net income	0	1,089	0	1,089
Net unrealized gain (loss) on derivative instruments designated as cash flow hedges	692	35	4,770	(295)
Net hedging (gain) loss reclassified into net income	216	91	(2,207)	482
Net defined benefit plan loss reclassified to net income	392	410	1,207	1,004
Total other comprehensive income (loss), net of tax	$ 622	$ 15,466	$ (14,768)	$ 51,584