Other Comprehensive Income (Loss) (Component Of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010	Jun. 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	10,186	23,264	47,006
Unrealized gains on available-for-sale securities, Tax expense (benefit)	3,565	8,143	16,452
Unrealized gains on available-for-sale securities, Net-of-tax amount	6,621	15,121	30,554
Unrealized net holding loss on cash flow hedge, Before-tax amount	(1,337)	(1,634)	(1,807)
Unrealized net holding loss on cash flow hedge, Tax expense (benefit)	(468)	(572)	(632)
Unrealized net holding loss on cash flow hedge, Net-of-tax amount	(869)	(1,062)	(1,175)
Total accumulated other comprehensive income (loss), Before-tax amount	(15,654)	(2,873)	24,430
Total accumulated other comprehensive income (loss), Tax expense (benefit)	(5,479)	(1,005)	8,551
Total accumulated other comprehensive income (loss), Net-of-tax amount	$ (10,175)	$ (1,868)	$ 15,879