Employee Benefit Plans - Funded status of Retirement Income Plan and amounts recognized in consolidated balance sheets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Contribution by employer for retirement income plan	$ 5,400,000
Settlement loss	(18,286,000)	$ (2,921,000)
Accumulated benefit obligation at end of year		29,651,000
Change in projected benefit obligation:
Projected benefit obligation at end of year	0
Change in Plan assets:
Employer contribution	5,400,000
Fair value of Plan assets at end of year	0
Retirement Income Plan
Defined Benefit Plan Disclosure [Line Items]
Contribution by employer for retirement income plan	5,454,000
Settlement loss	(18,286,000)	(2,921,000)
Change in projected benefit obligation:
Benefit obligation at beginning of year	29,651,000	41,038,000
Service cost	0	0
Interest cost	22,000	972,000	$ 988,000
Actuarial (gain) loss	(3,715,000)	(5,258,000)
Benefits paid	(836,000)	(3,248,000)
Transfer of assets	524,000
Refund related to Plan trust dissolution	(310,000)
Settlement	(25,122,000)	(3,853,000)
Projected benefit obligation at end of year		29,651,000	41,038,000
Change in Plan assets:
Fair value of Plan assets at beginning of year	20,041,000	35,339,000
Actual return on Plan assets	249,000	(8,197,000)
Employer contribution	5,454,000
Benefits paid	(836,000)	(3,248,000)
Settlement	(25,122,000)	(3,853,000)
Fair value of Plan assets at end of year		20,041,000	$ 35,339,000
Funded status at end of year		(9,610,000)
AMOUNTS (PRE-TAX) RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) CONSIST OF:
Net loss	0	22,476,000
Prior service cost (credit)	0	0
Net transition obligation (asset)	0	0
Before-tax amount	$ 0	$ 22,476,000