Employee Benefit Plans - Component of Net Periodic Pension Cost (Benefit) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Components of net periodic cost:
Interest cost	$ 0.1	$ 0.1	$ 0.1
Chesapeake Postretirement Plan
Assumptions
Funded status	(0.9)	(1.1)
FPU Medical Plan
Assumptions
Funded status	(0.3)	(0.4)
Chesapeake SERP
Components of net periodic cost:
Interest cost	0.1	0.1
Actuarial (gain) loss	0.0	0.0	0.0
Net periodic postretirement cost	$ 0.1	$ 0.1	$ 0.1
Assumptions
Discount rate	4.88%	5.00%	2.50%
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ 0.0	$ 0.0
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(0.2)	(0.2)
Defined Benefit Plan, Plan Assets, Contributions by Employer	0.2	0.2
Defined Benefit Plan, Plan Assets, Benefits Paid	(0.2)	(0.2)
Accrued pension cost	$ (1.5)	$ (1.6)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	5.40%	4.88%
FPU Pension Plan
Components of net periodic cost:
Interest cost	$ 2.4	$ 2.5	$ 1.8
Expected return on assets	(2.9)	(2.7)	(3.4)
Actuarial (gain) loss	0.3	0.4	0.5
Net periodic postretirement cost	$ (0.2)	$ 0.2	$ (1.1)
Assumptions
Discount rate	5.00%	5.25%	2.75%
Expected return on plan assets	6.00%	6.00%	6.00%
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ (2.0)	$ 0.5
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(4.6)	(3.2)
Defined Benefit Plan, Plan Assets, Amount	49.1	49.5	$ 46.2
Defined Benefit Plan, Plan Assets, Contributions by Employer	0.0	0.0
Defined Benefit Plan, Plan Assets, Benefits Paid	(4.6)	(3.2)
Accrued pension cost	$ 3.6	$ (0.2)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	5.50%	5.00%