Other Current and Long-Term Assets (Schedule Of Other Current Assets) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Other Assets, Noncurrent [Abstract]
Prepaid expenses (Note 2)	$ 32,646		$ 30,314
Taxes receivable	20,535		14,098
Customer acquisition costs	37,754		34,515
Contract assets	15,218		9,670
Deferred sales commissions	5,055		4,464
Other assets	14,966		15,159
Other current assets	$ 126,174	$ 107,228	$ 108,220