Employee Benefit Plans - Schedule of Funded Status of Benefit Obligation and Plan Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in benefit obligation:
Interest cost	$ 81	$ 50	$ 48
FPU Pension Plan
Change in benefit obligation:
Benefit obligation - beginning of year	49,941	67,030
Interest cost	2,495	1,781	1,714
Actuarial loss	454	(15,713)
Benefits paid	(3,233)	(3,157)
Benefit obligation - end of year	49,657	49,941	67,030
Change in plan assets:
Balance, beginning of year	46,203	58,712
Actual return on plan assets	6,462	(9,552)
Employer contributions	0	200
Benefits paid	(3,233)	(3,157)
Balance, end of year	49,432	46,203	$ 58,712
Reconciliation:
Accrued pension cost	$ (225)	$ (3,738)
Assumptions:
Discount rate	5.00%	5.25%
Expected return on plan assets	6.00%	6.00%	6.00%
Chesapeake SERP
Change in benefit obligation:
Benefit obligation - beginning of year	$ 1,659	$ 2,096
Interest cost	81	50
Actuarial loss	48	(335)
Benefits paid	(152)	(152)
Benefit obligation - end of year	1,636	1,659	$ 2,096
Change in plan assets:
Employer contributions	152	152
Benefits paid	(152)	(152)
Reconciliation:
Accrued pension cost	$ (1,636)	$ (1,659)
Assumptions:
Discount rate	4.88%	5.00%
Chesapeake Postretirement Plan
Reconciliation:
Funded status	$ (1,100)	$ (600)
FPU Medical Plan
Reconciliation:
Funded status	$ (400)	$ (700)