Stockholders' Equity (Schedule Of Stock Option Activity) (Details) - Stock Option [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Balance as of December 31, Number of Shares	5,897	6,095	5,998
Balance as of December 31, Weighted-Average Exercise Per Share	$ 4.17	$ 4.14	$ 4.05
Options forfeited, Number of Shares	(262)	(705)	(966)
Options forfeited, Weighted-Average Exercise Per Share	$ 5.77	$ 5.10	$ 5.45
Options granted, Number of Shares	1,414	1,740	1,637
Options granted, Weighted-Average Exercise Per Share	$ 8.83	$ 4.85	$ 4.76
Options exercised, Number of Shares	(1,022)	(1,233)	(574)
Options exercised, Weighted-Average Exercise Per Share	$ 4.48	$ 4.43	$ 2.82
Balance as of December 31, Number of Shares	6,027	5,897	6,095	5,998
Balance as of December 31, Weighted-Average Exercise Per Share	$ 5.14	$ 4.17	$ 4.14	$ 4.05
Options outstanding Weighted-Average Remaining Contractual Term (Years)	6 years 26 days	6 years 29 days	5 years 7 months 28 days	6 years 22 days
Balance as of December 31, Aggregate Intrinsic Value	$ 24,462	$ 27,066	$ 7,199	$ 5,575
Vested and expected to vest after December 31, 2015 Number of Shares	5,564
Vested and expected to vest after December 31, 2015 Weighted-Average Exercise Per Share	$ 4.97
Vested and expected to vest after December 31, 2015 Weighted-Average Remaining Contractual Term (Years)	5 years 10 months 2 days
Vested and expected to vest after December 31, 2015 Aggregate Intrinsic Value	$ 23,556
Exercisable as of December 31, Number of Shares	3,600
Exercisable as of December 31, Weighted-Average Exercise Per Share	$ 3.91
Exercisable as of December 31, Weighted-Average Remaining Contractual Term (Years)	4 years 4 months 6 days
Exercisable as of December 31, Aggregate Intrinsic Value	$ 19,030