Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements of Comprehensive Income [Abstract]
Net Income	$ 12,374	$ 9,188
Other Comprehensive Income (Loss), Net of Tax:
Net unrealized gains (losses) on investment securities available-for-sale, net of tax expense (benefit) of $469 in 2012 and $(347) in 2011	872	(643)
Adjustment for pension and other postretirement benefits, net of tax expense of $186 in 2012 and $63 in 2011	346	117
Total other comprehensive income (loss), net of tax	1,218	(526)
Comprehensive Income	$ 13,592	$ 8,662