Comprehensive Income - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Employee Benefits	$ 10,212	$ 9,727	$ 20,595	$ 19,046
Total before Tax	11,721	11,240	21,895	22,124
Provision for income taxes	(2,562)	(2,306)	(4,609)	(4,456)
Net Income	9,159	8,934	17,286	17,668
Amounts Reclassified from Accumulated Other Comprehensive Income | Amortization of Defined Benefit Pension, Prior-Service Costs
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Employee Benefits	(52)	(57)	(106)	(113)
Amounts Reclassified from Accumulated Other Comprehensive Income | Amortization of Defined Benefit Pension, Actuarial Loss
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Salaries and Employee Benefits	(78)	(179)	(114)	(342)
Amounts Reclassified from Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plans Adjustment
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total before Tax	(130)	(236)	(220)	(455)
Provision for income taxes	33	60	57	116
Net Income	$ (97)	$ (176)	$ (163)	$ (339)