Retirement Benefit Plans (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Net Periodic Benefit Cost [Line Items]
Interest credit under cash balance plan	0.03
Employer matching contribution, percentage	5.00%
Service cost and interest cost			$ 3,300,000
Unamortized net loss			$ 7,200,000
Benefit obligation from lump sum payment to total benefit obligation ratio			8.06%
Defined benefit plan, net periodic benefit cost, loss due to settlement			$ 577,000
Employees' Pension Plan
Net Periodic Benefit Cost [Line Items]
Assumptions used calculating benefit obligation, interest rate to annuitize cash balance account			509.00%
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	$ 413,000	$ 488,000
Interest Cost	530,000	367,000
Expected Return on Plan Assets	(857,000)	(1,099,000)
Amortization of Prior Service Cost	16,000	19,000
Amortization of Net Loss (Gain)	36,000	0
Net Periodic Cost	138,000	(225,000)
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			560.00%
Defined benefit plan, amortization of service cost	12 years 6 months
Defined benefit plan, benefit obligation, period increase (decrease)	$ 122,797
Service Cost	163,000	147,000
Interest Cost	62,000	51,000
Expected Return on Plan Assets	0	0
Amortization of Prior Service Cost	10,000	11,000
Amortization of Net Loss (Gain)	18,000	39,000
Net Periodic Cost	253,000	248,000
Plan Contributions During the Period	116,000	116,000
Estimated Future Contributions in the Current Fiscal Year	154,000
Post-Retirement Benefit Plans
Net Periodic Benefit Cost [Line Items]
Assumptions used calculating benefit obligation, interest rate to annuitize cash balance account			5.41%
Service Cost	18,000	27,000
Interest Cost	87,000	64,000
Expected Return on Plan Assets	0	0
Amortization of Prior Service Cost	26,000	27,000
Amortization of Net Loss (Gain)	(79,000)	(32,000)
Net Periodic Cost	52,000	86,000
Plan Contributions During the Period	27,000	$ 55,000
Estimated Future Contributions in the Current Fiscal Year	$ 81,000
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%