Other Current and Long-Term Assets (Schedule Of Other Current Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Current and Long-Term Assets [Abstract]
Prepaid expenses	$ 28,720	$ 28,967
Taxes receivable	26,207	35,475
Customer acquisition costs (Notes 2 and 3)	30,354	23,520
Contract assets (Notes 2 and 3)	5,085
Deferred sales commissions (Notes 2 and 3)	4,369
Other assets (Notes 2 and 3)	8,839	13,178
Other current assets	$ 103,574	$ 101,140