Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net Income	$ 56,808	$ 51,008	$ 43,050
Other Comprehensive Income (Loss), Net of Tax:
Change in net unrealized gains (losses) on investment securities available-for-sale, net of tax expense (benefit) of $(3,325), $505 and $10 for the years ended December 31, 2013, 2012 and 2011, respectively	(6,177)	938	19
Reclassification adjustment for realized gain on sale of investment securities available-for-sale included in net income, net of tax expense of $311 for the year ended December 31, 2013	(577)	0	0
Change in adjustment for pension and other postretirement benefits, net of tax benefit (expense) of $(9,344), $3,623 and $6,051 for the years ended December 31, 2013, 2012 and 2011, respectively	17,353	(6,728)	(11,237)
Total other comprehensive income (loss), net of tax	10,599	(5,790)	(11,218)
Comprehensive Income	$ 67,407	$ 45,218	$ 31,832