Other Current and Long-Term Assets (Schedule Of Other Current Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Other Assets, Noncurrent [Abstract]
Customer acquisition costs	$ 48,164	$ 43,751
Prepaid expenses	37,462	34,556
Contract assets, net	31,446	23,837
Taxes receivable	16,823	19,476
Deferred sales commissions	6,302	5,738
Other assets	17,393	10,150
Other current assets	$ 157,590	$ 137,508