Other Current and Long-Term Assets (Schedule Of Other Long-term Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Other Assets, Noncurrent [Abstract]
Investment in long-term product supply arrangements	$ 13,082	$ 10,894
Taxes receivable	14,982	19,219
Customer acquisition costs	93,288	89,862
Contract assets	55,283	31,269
Deferred sales commissions	10,178	9,470
Deferred income taxes	8,399	8,481
Other assets	29,493	20,398
Other long-term assets	$ 224,705	$ 189,593