Financial Instruments And Investments (Sale Of Securities And The Related Effects On Pre-Tax Income ) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Investment [Line Items]
Proceeds from sales or maturities of available-for-sale securities	$ 7,116	$ 2,608	$ 22,887	$ 14,365	$ 34,477	$ 48,871
Gross realized gains included in pre-tax income	55	0	113	9	121	3,873
Gross realized losses included in pre-tax income	(196)	(147)	(1,083)	(674)	(1,871)	(1,269)
Net gains (losses) included in pre-tax income	$ (141)	$ (147)	$ (970)	$ (665)	$ (1,750)	$ 2,604