Accumulated Other Comprehensive Income (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net securities gains (losses)	$ 10	$ (1)	$ 14	$ (1)
Income tax expense	(2,319)	(3,990)	(5,171)	(7,747)
Unrealized gain (loss) on securities, net of tax	6,923	8,488	14,684	16,319
Change in funded status of post retirement benefits	819	115	3,283	230
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)	3,291	(231)
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)	10	(1)	14	(1)
Income tax expense	3	0	6	0
Unrealized gain (loss) on securities, net of tax	7	(1)	8	(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)	122	(2,189)	244
Unrealized gain (loss) on securities, net of tax	819	(115)	3,283	(230)
Change in funded status of post retirement benefits	$ 1,365	$ (237)	$ 5,472	$ (474)