Other Current and Long-Term Assets (Schedule Of Other Current Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Other Assets, Noncurrent [Abstract]
Prepaid expenses	$ 31,593		$ 30,314
Taxes receivable	13,813		14,098
Customer acquisition costs	35,495		34,515
Contract assets	11,669		9,670
Deferred sales commissions	4,664		4,464
Other assets	13,169		15,159
Other current assets	$ 110,403	$ (992)	$ 108,220