Employee Benefit Plans - Funded status of Retirement Income Plan and amounts recognized in consolidated balance sheets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation at end of year	$ 29,651,000	$ 41,038,000
Retirement Income Plan
Change in projected benefit obligation:
Benefit obligation at beginning of year	41,038,000	41,120,000
Service cost	0	0
Interest cost	972,000	988,000	$ 1,645,000
Actuarial (gain) loss	(5,258,000)	1,365,000
Benefits paid	(3,248,000)	(2,435,000)
Settlement	(3,853,000)
Projected benefit obligation at end of year	29,651,000	41,038,000	41,120,000
Change in Plan assets:
Fair value of Plan assets at beginning of year	35,339,000	39,068,000
Actual return on Plan assets	(8,197,000)	(1,294,000)
Employer contribution	0	0
Benefits paid	(3,248,000)	(2,435,000)
Settlement	(3,853,000)
Fair value of Plan assets at end of year	20,041,000	35,339,000	39,068,000
Funded status at end of year	(9,610,000)	(5,699,000)
AMOUNTS (PRE-TAX) RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) CONSIST OF:
Net loss	22,476,000	23,468,000
Prior service cost (credit)	0	0
Net transition obligation (asset)	0	0	$ 0
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax, Total	$ 22,476,000	$ 23,468,000