Other Current and Long-Term Assets (Schedule Of Other Long-term Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Other Assets, Noncurrent [Abstract]
Investment in long-term product supply arrangements	$ 11,344	$ 9,949
Customer acquisition costs (Notes 2 and 3)	86,147	64,670
Contract assets (Notes 2 and 3)	14,903	0
Deferred sales commissions (Notes 2 and 3)	8,349	0
Deferred income taxes (Note 2)	8,723	7,698
Other assets (Notes 2 and 3)	22,356	36,299
Other long-term assets	$ 151,822	$ 118,616