Financial Instruments And Investments (Sale Of Securities And The Related Effects On Pre-Tax Income ) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investment [Line Items]
Proceeds from sales of available-for-sale securities	$ 102,567	$ 108,311	$ 56,148
Gross realized gains included in pre-tax income	12,379	7,858	986
Gross realized losses included in pre-tax income	(927)	(508)	(433)
Gross unrealized losses included in pre-tax income	(338)	0	0
Net gains (losses) in pre-tax income	11,114	7,350	553
Net unrealized holding gains (losses) included in accumulated other comprehensive income	(2,906)	10,827	17,699
Net (gains) losses reclassified out of accumulated other comprehensive income	(11,114)	(7,350)	(553)
Net gains (losses) in other comprehensive income	$ (14,020)	$ 3,477	$ 17,146