Benefit Plans - Change in Projected Benefit Obligation, Change in Fair Value of Plan Assets, and Funded Status of the Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	$ 14,899
Projected benefit obligation at end of year	14,571	$ 14,899
Change in fair value of plan assets:
Fair value of plan assets at beginning of year	274,696
Fair value of plan assets at end of year	302,034	274,696
Funded status of the plan
Accumulated benefit obligation	14,571	14,899
Accrued interest receivable	826	710
Pension
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	175,496	180,204
Acquisition	0	49,008
Interest cost	8,923	5,373	$ 3,510
Actuarial gain (loss)	7,604	(48,109)
Benefits paid	(12,105)	(10,980)
Projected benefit obligation at end of year	179,918	175,496	180,204
Change in fair value of plan assets:
Fair value of plan assets at beginning of year	275,406	278,420
Acquisition	0	53,433
Actual return on plan assets	37,993	(47,029)
Employer contributions	1,566	1,562
Benefits paid	(12,105)	(10,980)
Fair value of plan assets at end of year	302,860	275,406	278,420
Funded status of the plan
Assets (liabilities) recognized	122,942	99,910
Accumulated benefit obligation	179,918	175,496
OPEB
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	5,981	0
Acquisition	0	7,445
Interest cost	279	174
Actuarial gain (loss)	(161)	(975)
Benefits paid	(648)	(663)
Projected benefit obligation at end of year	5,451	5,981	0
Change in fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Acquisition	0	0
Actual return on plan assets	0	0
Employer contributions	648	663
Benefits paid	(648)	(663)
Fair value of plan assets at end of year	0	0	$ 0
Funded status of the plan
Assets (liabilities) recognized	(5,451)	(5,981)
Accumulated benefit obligation	$ 5,451	$ 5,981