Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Net income	$ 13,234	$ 12,374
Other comprehensive income (loss), net of tax:
Net unrealized gains on investment securities available-for-sale, net of tax expense of $227 and $469 for the three months ended March 31, 2013, and 2012, respectively	420	872
Reclassification adjustment for realized gain on sale of investment securities available-for-sale included in net income, net of tax expense of $296 for the three months ended March 31, 2013	(551)	0
Adjustment for pension and other postretirement benefits, net of tax expense of $332 and $186 for the three months ended March 31, 2013, and 2012, respectively	616	346
Total other comprehensive income, net of tax	485	1,218
Comprehensive income	$ 13,719	$ 13,592