Convertible Debt (Schedule Of Interest Expense Recognized) (Details) - 3.375% Convertible Notes [Member] - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Debt Instrument [Line Items]
3.375% contractual coupon		$ 1,814	$ 1,814	$ 3,628	$ 3,628
Amortization of debt discount		1,293	1,213	2,565	2,406
Amortization of debt issuance costs		190	169	409	334
Additional interest on Convertible Notes	[1]				1,370
Interest expense		$ 3,297	$ 3,196	$ 6,602	$ 7,738
Interest rate		3.375%		3.375%

[1] During the six months ended June 30, 2019, additional nonrecurring interest expense was incurred pursuant to the notes’ indenture related to the removal of the restrictive legend and assignment of the unrestricted CUSIP on the Convertible Notes.