Employee Benefit Plans - Schedule of defined benefit plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined benefit plans
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$ 450,022	$ 603,309
Interest cost	23,579	17,332	$ 16,465
Benefits paid	(33,750)	(33,521)
Actuarial (gains)/losses	9,142	(137,098)
Projected benefit obligation at end of year	448,993	450,022	603,309
Plan assets:
Fair value at beginning of year	383,725	517,148
Actual return on plan assets	37,454	(124,901)
Company contributions	0	24,999
Benefits paid	(33,750)	(33,521)
Fair value at end of year	387,429	383,725	517,148
Funded status	(61,564)	(66,297)
Amounts recognized in Consolidated Balance Sheets:
Current liabilities	0	0
Noncurrent liabilities	(61,564)	(66,297)
Total	(61,564)	(66,297)
Amounts Recognized in Accumulated Other Comprehensive Loss:
Net actuarial loss	95,793	98,884
Prior service cost	334	352
SERPs
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	13,393	18,023
Interest cost	708	509
Benefits paid	(1,161)	(1,541)
Actuarial (gains)/losses	497	(3,598)
Projected benefit obligation at end of year	13,437	13,393	18,023
Plan assets:
Fair value at beginning of year	0	0
Actual return on plan assets	0	0
Company contributions	1,161	1,541
Benefits paid	(1,161)	(1,541)
Fair value at end of year	0	0	$ 0
Funded status	(13,437)	(13,393)
Amounts recognized in Consolidated Balance Sheets:
Current liabilities	(1,350)	(1,411)
Noncurrent liabilities	(12,087)	(11,982)
Total	(13,437)	(13,393)
Amounts Recognized in Accumulated Other Comprehensive Loss:
Net actuarial loss	3,838	3,467
Prior service cost	$ 0	$ 0