Accumulated Other Comprehensive Income (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net securities gains (losses)	$ 3	$ 4
Income tax expense	(10,666)	(2,852)
Unrealized gain (loss) on securities, net of tax	13,675	7,761
Change in funded status of post retirement benefits	304	2,464
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	305	(490)
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)	3	4
Income tax expense	(2)	(2)
Unrealized gain (loss) on securities, net of tax	1	2
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	(203)	328
Unrealized gain (loss) on securities, net of tax	304	(492)
Change in funded status of post retirement benefits	$ 507	$ (820)