Other Comprehensive Income (Loss) (Component Of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010
Other Comprehensive Income (Loss) [Abstract]
Changes in pension plan assets and benefit obligations, Before-tax amount	$ (24,503)	$ (24,503)	$ (20,769)
Changes in pension plan assets and benefit obligations, Tax expense (benefit)	(8,576)	(8,576)	(7,269)
Changes in pension plan assets and benefit obligations, Net-of-tax amount	(15,927)	(15,927)	(13,500)
Unrealized gains on available-for-sale securities, Before-tax amount	24,253	23,264	41,685
Unrealized gains on available-for-sale securities, Tax expense (benefit)	8,488	8,143	14,590
Unrealized gains on available-for-sale securities, Net-of-tax amount	15,765	15,121	27,095
Unrealized net holding loss on cash flow hedge, Before-tax amount	(1,099)	(1,634)	(1,909)
Unrealized net holding loss on cash flow hedge, Tax expense (benefit)	(385)	(572)	(668)
Unrealized net holding loss on cash flow hedge, Net-of-tax amount	(714)	(1,062)	(1,241)
Total accumulated other comprehensive income (loss), Before-tax amount	(1,349)	(2,873)	19,007
Total accumulated other comprehensive income (loss), Tax expense (benefit)	(473)	(1,005)	6,653
Total accumulated other comprehensive income (loss), Net-of-tax amount	$ (876)	$ (1,868)	$ 12,354