Goodwill (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Balance at beginning of period	$ 181,230	$ 187,875
Acquisitions and adjustments	31,479	52
Effect of foreign currency exchange rates	18,173	(6,697)
Balance at end of period	230,882	181,230
Americas [Member]
Goodwill [Line Items]
Balance at beginning of period
Acquisitions and adjustments
Effect of foreign currency exchange rates
Balance at end of period
EMEA [Member]
Goodwill [Line Items]
Balance at beginning of period	144,971	150,521
Acquisitions and adjustments	31,438
Acquisitions and adjustments		(137)
Effect of foreign currency exchange rates	15,539	(5,413)
Balance at end of period	191,948	144,971
Asia Pacific [Member]
Goodwill [Line Items]
Balance at beginning of period	36,259	37,354
Acquisitions and adjustments	41	189
Effect of foreign currency exchange rates	2,634	(1,284)
Balance at end of period	$ 38,934	$ 36,259