Income Taxes (Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 32,969	$ 40,939
Stock-based compensation	23,652	23,258
Employee benefits	17,187	17,044
Uncertain tax positions	11,562	10,233
Deferred revenue	6,382	8,603
Research and development credits	3,889	3,562
Allowance for doubtful accounts	2,078	1,888
Other	3,163	3,240
Valuation allowance	(1,625)	(603)
Deferred tax assets	99,257	108,164
Other intangible assets	(56,195)	(73,933)
Property and equipment	(2,994)	(3,426)
Deferred tax liabilities	(59,189)	(77,359)
Net deferred tax assets	$ 40,068	$ 30,805