Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income	$ 10,714	$ 10,252	$ 33,533	$ 29,183
Net unrealized holding gain (loss) on securities available for sale	(1,269)	1,461	17,615	(27,793)
Reclassification adjustments for net gain recognized in income	(376)	0	(382)	(1,434)
Tax effect	650	(583)	(6,893)	11,654
Net unrealized gain (loss) on securities available for sale, net of tax	(995)	878	10,340	(17,573)
Amortization of net actuarial (gain) loss	(77)	117	(223)	350
Amortization of prior service credit	239	(66)	149	(197)
Tax effect	(64)	(21)	29	(61)
Amortization of net actuarial (gain) loss and prior service credit on pension and postretirement plans, net of tax	98	30	(45)	92
Other comprehensive income (loss), net of tax	(897)	908	10,295	(17,481)
Comprehensive income	$ 9,817	$ 11,160	$ 43,828	$ 11,702