Other Current and Long-Term Assets (Schedule Of Other Long-term Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Other Assets, Noncurrent [Abstract]
Investment in long-term product supply arrangements	$ 12,386	$ 10,894
Customer acquisition costs	90,114	89,862
Contract assets	47,344	31,269
Deferred sales commissions	9,890	9,470
Deferred income taxes	8,739	8,481
Other assets	38,783	39,617
Other long-term assets	$ 207,256	$ 189,593