Income Taxes (Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 21,391	$ 32,969
Stock-based compensation	17,825	23,652
Uncertain tax positions	15,424	11,562
Employee benefits	8,603	17,187
Deferred revenue	5,134	6,382
Research and development credits	3,699	3,889
Allowance for doubtful accounts	1,462	2,078
Other	2,003	3,114
Valuation allowance	(1,906)	(1,625)
Deferred tax assets	73,635	99,208
Other intangible assets	(29,924)	(56,195)
Property and equipment	(1,557)	(2,994)
Unremitted foreign earnings	(1,504)
Unremitted foreign earnings		49
Deferred tax liabilities	(32,985)	(59,140)
Net deferred tax assets	$ 40,650	$ 40,068