Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Net of tax amount	$ 151,156,000	$ 140,699,000	$ 145,176,000	$ 134,840,000	$ 129,005,000	$ 127,528,000
Debt Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Before tax	9,602,000		12,571,000
AOCI, Tax effect	(2,017,000)		(2,640,000)
AOCI, Net of tax amount	7,585,000		9,931,000
Pension [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Before tax	(8,533,000)		(8,533,000)
AOCI, Tax effect	1,792,000		1,792,000
AOCI, Net of tax amount	(6,741,000)		(6,741,000)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI, Net of tax amount	$ 844,000	$ (5,166,000)	$ 3,190,000	$ (725,000)	$ (4,360,000)	$ (5,986,000)