Reclassification Adjustments Out of Other Comprehensive (Loss) Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Gain (Loss) on Sale of Securities, Net	$ 1,145	$ 455
Salaries and employee benefits	27,047	26,725
Income tax expense	3,357	5,853
Net income	7,649	13,650
Total reclassification during the period, net of tax	1,194	789
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Gain (Loss) on Sale of Securities, Net	1,145	455
Income tax expense	(454)	(182)
Net income	691	273
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	323	341
Net income	503	516
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Amortization of net gains [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	882	911
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Amortization of prior service costs [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	$ (56)	$ (54)