Financial Instruments And Investments (Sale Of Securities And The Related Effects On Pre-Tax Income ) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Financial Instruments And Investments [Abstract]
Proceeds from sales of available-for-sale securities	$ 14,582	$ 31,435	$ 74,095	$ 67,841	$ 89,180	$ 82,561
Gross realized gains included in pre-tax income	447	552	1,526	1,248	1,757	1,657
Gross realized losses included in pre-tax income	(129)	(289)	(2,276)	(583)	(2,414)	(512)
Gross unrealized holding losses included In pre-tax income	0	(1,547)	(166)	(1,746)	(536)	(1,746)
Net gains (losses) in pre-tax income	318	(1,284)	(916)	(1,081)	(1,193)	(601)
Net unrealized holding gains (losses) included in accumulated other comprehensive income	6,169	(7,503)	11,986	(4,914)	18,470	(1,290)
Net (gains) losses reclassified out of accumulated other comprehensive income	(318)	1,284	916	1,081	1,193	601
Net gains (losses) in other comprehensive income	$ 5,851	$ (6,219)	$ 12,902	$ (3,833)	$ 19,663	$ (689)