Financial Instruments And Investments (Sale Of Securities And The Related Effects On Pre-Tax Income ) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Investment [Line Items]
Proceeds from sales of available-for-sale securities	$ 26,618	$ 10,980	$ 63,776	$ 47,355	$ 124,732	$ 74,083
Gross realized gains included in pre-tax income	4,515	1,239	8,330	4,502	12,467	4,895
Gross realized losses included in pre-tax income	(191)	(415)	(443)	(711)	(1,021)	(838)
Net gains (losses) in pre-tax income	4,324	824	7,887	3,791	11,446	4,057
Net unrealized holding gains (losses) included in accumulated other comprehensive income	(8,092)	897	(8,641)	7,965	(5,779)	16,803
Net (gains) losses reclassified out of accumulated other comprehensive income	(4,324)	(824)	(7,887)	(3,791)	(11,446)	(4,057)
Net gains (losses) in other comprehensive income	$ (12,416)	$ 73	$ (16,528)	$ 4,174	$ (17,225)	$ 12,746