Accumulated Other Comprehensive Income (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net securities gains (losses)	$ 6	$ 3	$ 18	$ 5
Income tax expense	(2,579)	(2,656)	(8,000)	(8,941)
Unrealized gain (loss) on securities, net of tax	12,257	11,313	34,508	35,527
Change in funded status of post retirement benefits	303	281	910	843
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	(299)	(279)	(897)	(839)
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)	6	3	18	5
Income tax expense	(2)	(1)	(5)	(1)
Unrealized gain (loss) on securities, net of tax	4	2	13	4
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	86	81	258	242
Unrealized gain (loss) on securities, net of tax	(303)	(281)	(910)	(843)
Change in funded status of post retirement benefits	$ (389)	$ (362)	$ (1,168)	$ (1,085)