Retirement Benefit Plans (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	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%		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	$ 384,000	$ 451,000	$ 797,000	$ 939,000
Interest Cost	519,000	352,000	1,049,000	719,000
Expected Return on Plan Assets	(851,000)	(1,058,000)	(1,708,000)	(2,157,000)
Amortization of Prior Service Cost	15,000	20,000	31,000	39,000
Amortization of Net Loss (Gain)	23,000	0	59,000	0
Net Periodic Cost	90,000	(235,000)	228,000	(460,000)
Plan Contributions During the Period	0	0	0	0
Estimated Future Contributions in the Current Fiscal Year	0		$ 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	122,000	271,000	285,000	418,000
Interest Cost	97,000	61,000	159,000	112,000
Expected Return on Plan Assets	0	0	0	0
Amortization of Prior Service Cost	10,000	11,000	20,000	22,000
Amortization of Net Loss (Gain)	19,000	67,000	37,000	106,000
Net Periodic Cost	248,000	410,000	501,000	658,000
Plan Contributions During the Period	110,000	115,000	226,000	231,000
Estimated Future Contributions in the Current Fiscal Year	226,000		226,000
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	10,000	18,000	28,000	45,000
Interest Cost	80,000	60,000	167,000	124,000
Expected Return on Plan Assets	0	0	0	0
Amortization of Prior Service Cost	26,000	26,000	52,000	53,000
Amortization of Net Loss (Gain)	(98,000)	(46,000)	(177,000)	(78,000)
Net Periodic Cost	18,000	58,000	70,000	144,000
Plan Contributions During the Period	20,000	$ 33,000	47,000	$ 88,000
Estimated Future Contributions in the Current Fiscal Year	$ 47,000		$ 47,000
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%