Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	$ 548,185	$ 538,257	$ 501,718	$ 489,871	$ 538,257	$ 489,871
Other comprehensive income (loss) - before reclassifications	685		5,237		8,630	8,535
Amount reclassified from accumulated other comprehensive income	(141)		0		(1,155)	0
Other comprehensive income, net of tax	544	6,931	5,237	3,298	7,475	8,535
Balance	553,421	548,185	515,630	501,718	553,421	515,630
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	11,392	4,461	(7,011)	(10,309)	4,461	(10,309)
Other comprehensive income, net of tax	544	6,931	5,237	3,298
Balance	11,936	11,392	(1,774)	(7,011)	11,936	(1,774)
Net Unrealized Holding (Gain) Loss on Securities Available for Sale, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	7,376	286	(7,020)	(10,416)	286	(10,416)
Other comprehensive income (loss) - before reclassifications	685		5,313		8,630	8,709
Amount reclassified from accumulated other comprehensive income	0		0		(855)	0
Other comprehensive income, net of tax	685		5,313		7,775	8,709
Balance	8,061	7,376	(1,707)	(7,020)	8,061	(1,707)
Net Change in Overfunded Position in Pension and Postretirement Plans Arising During the Year, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	4,840	4,840	423	423	4,840	423
Other comprehensive income (loss) - before reclassifications	0		0		0	0
Amount reclassified from accumulated other comprehensive income	0		0		0	0
Other comprehensive income, net of tax	0		0		0	0
Balance	4,840	4,840	423	423	4,840	423
Net Change in Net Actuarial (Gain) Loss and Prior Service Credit on Pension and Postretirement Benefit Plans, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(824)	(665)	(414)	(316)	(665)	(316)
Other comprehensive income (loss) - before reclassifications	0		(76)		0	(174)
Amount reclassified from accumulated other comprehensive income	(141)		0		(300)	0
Other comprehensive income, net of tax	(141)		(76)		(300)	(174)
Balance	$ (965)	$ (824)	$ (490)	$ (414)	$ (965)	$ (490)