Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income	$ 14,993	$ 13,106	$ 42,430	$ 39,346
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on investment securities available-for-sale, net of tax expense (benefit) of $(392) and $491 for the three months ended September 30, 2013 and 2012, respectively, and $(2,879) and $746 for the nine months ended September 30, 2013 and 2012, respectively	(726)	911	(5,347)	1,385
Reclassification adjustment for realized gain on sale of investment securities available-for-sale included in net income, net of tax expense of $300 for the nine months ended September 30, 2013	0	0	(558)	0
Adjustment for pension and other postretirement benefits, net of tax expense of $332 and $187 for the three months ended September 30, 2013 and 2012, respectively, and $996 and $559 for the nine months ended September 30, 2013 and 2012, respectively	616	347	1,849	1,038
Total other comprehensive income (loss), net of tax	(110)	1,258	(4,056)	2,423
Comprehensive income	$ 14,883	$ 14,364	$ 38,374	$ 41,769