Other Current and Long-Term Assets (Schedule Of Other Current Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Other Assets, Noncurrent [Abstract]
Prepaid expenses (Note 2)	$ 28,958		$ 30,314
Taxes receivable	22,744		14,098
Customer acquisition costs	36,291		34,515
Contract assets	13,008		9,670
Deferred sales commissions	4,861		4,464
Other assets	12,561		15,159
Other current assets	$ 118,423	$ 107,228	$ 108,220