Derivatives (Summary Of The Fair Value Of The Equity Index Put Options) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Option Indexed to Issuer's Equity [Line Items]
Equity index put option liability	$ 9,088		$ 9,088		$ 5,584
Net derivative gain (loss)	11,869	$ 353	(3,504)	$ 3,584
Equity Index Put Option Contracts [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Option Indexed to Issuer's Equity [Line Items]
Equity index put option liability	9,088		9,088		$ 5,584
Net derivative gain (loss)	$ 11,869	$ 353	$ (3,504)	$ 3,584