Accumulated Other Comprehensive Income (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net securities gains (losses)	$ 9	$ 0	$ 23	$ (1)
Income tax expense	(2,927)	(3,156)	(8,098)	(10,903)
Unrealized gain (loss) on securities, net of tax	8,398	8,272	23,082	24,591
Change in funded status of post retirement benefits	819	116	4,102	346
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Unrealized gain (loss) on securities, net of tax	826	(116)	4,117	(347)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net securities gains (losses)	9	0	23	(1)
Income tax expense	(2)	0	(8)	0
Unrealized gain (loss) on securities, net of tax	7	0	15	(1)
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income tax expense	(546)	121	(2,735)	365
Unrealized gain (loss) on securities, net of tax	819	(116)	4,102	(346)
Change in funded status of post retirement benefits	$ 1,365	$ (237)	$ 6,837	$ (711)