Retirement Benefit Plans (Details)	3 Months Ended
	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021
Net Periodic Benefit Cost [Line Items]
Interest credit under cash balance plan	0.03
Employer matching contribution, percentage	5.00%
Employees' Pension Plan
Net Periodic Benefit Cost [Line Items]
Assumptions used calculating benefit obligation, interest rate to annuitize cash balance account			1.02%
Defined benefit plan, increase in benefit payable, percent	3.00%
Defined benefit plan, benefit obligation, increase (decrease) for plan amendment	$ 351,638
Defined benefit plan, amortization of service cost	9 years 8 months 12 days
Service Cost	$ 488,000	$ 460,000
Interest Cost	367,000	340,000
Expected Return on Plan Assets	(1,099,000)	(950,000)
Amortization of Prior Service (Credit) Cost	19,000	20,000
Amortization of Net Loss (Gain)	0	0
Net Periodic (Benefit) Cost	(225,000)	(130,000)
Plan Contributions During the Period	0	0
Estimated Future Contributions in the Current Fiscal Year	$ 0
Select Executive Retirement Plan
Net Periodic Benefit Cost [Line Items]
Assumptions used calculating benefit obligation, interest rate to annuitize cash balance account			2.72%
Defined benefit plan, amortization of service cost	12 years 6 months
Defined benefit plan, benefit obligation, period increase (decrease)	$ 122,797
Service Cost	147,000	118,000
Interest Cost	51,000	45,000
Expected Return on Plan Assets	0	0
Amortization of Prior Service (Credit) Cost	11,000	12,000
Amortization of Net Loss (Gain)	39,000	38,000
Net Periodic (Benefit) Cost	248,000	213,000
Plan Contributions During the Period	116,000	118,000
Estimated Future Contributions in the Current Fiscal Year	348,000
Post-Retirement Benefit Plans
Net Periodic Benefit Cost [Line Items]
Assumptions used calculating benefit obligation, interest rate to annuitize cash balance account			3.08%
Service Cost	27,000	31,000
Interest Cost	64,000	67,000
Expected Return on Plan Assets	0	0
Amortization of Prior Service (Credit) Cost	27,000	27,000
Amortization of Net Loss (Gain)	(32,000)	8,000
Net Periodic (Benefit) Cost	86,000	133,000
Plan Contributions During the Period	55,000	$ 28,000
Estimated Future Contributions in the Current Fiscal Year	$ 165,000
On or Subsequent to January 1, 2003
Net Periodic Benefit Cost [Line Items]
Service credits, percent of eligible salaries	6.00%
Minimum | Prior to January 1, 2003
Net Periodic Benefit Cost [Line Items]
Service credits, percent of eligible salaries	6.00%
Maximum | Prior to January 1, 2003
Net Periodic Benefit Cost [Line Items]
Service credits, percent of eligible salaries	12.00%