Fair Value Measurement (Schedule Of Fair Value Of Debt Instruments) (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible senior notes		$ 187,955	$ 207,338
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible senior notes	[1]	$ 193,534	$ 192,262

[1] The carrying value of the convertible debt instrument presented in the table above represents the face value of the convertible note less unamortized debt discount.