Employee Benefit Plans - Component of Net Periodic Pension Cost (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Components of net periodic cost:
Interest cost	$ 50	$ 48	$ 63
Chesapeake Postretirement Plan
Assumptions
Funded status	(600)	(900)
FPU Medical Plan
Assumptions
Funded status	(700)	(1,000)
Chesapeake SERP
Components of net periodic cost:
Interest cost	50	48
Actuarial (gain) loss	28	28	20
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0	0
Net periodic postretirement cost	$ 78	$ 76	$ 83
Assumptions
Discount rate	2.50%	2.25%	3.00%
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ (335)	$ (12)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(152)	(152)
Defined Benefit Plan, Plan Assets, Contributions by Employer	152	152
Defined Benefit Plan, Plan Assets, Benefits Paid	(152)	(152)
Accrued pension cost	$ (1,659)	$ (2,096)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	5.00%	2.50%
Chesapeake Pension Plan
Components of net periodic cost:
Interest cost	$ 0	$ 141	$ 176
Expected return on assets	0	(166)	(157)
Actuarial (gain) loss	0	257	243
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	1,810	203
Net periodic pension cost	0	2,042	465
Amortization of pre-merger regulatory asset	0	0	0
Net periodic postretirement cost	$ 0	$ 2,042	$ 465
Assumptions
Discount rate	0.00%	2.25%	3.00%
Expected return on plan assets	0.00%	3.50%	3.50%
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ 0	$ (371)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	0	(32)
Defined Benefit Plan, Plan Assets, Amount	0	0	$ 4,609
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	1,544
Defined Benefit Plan, Plan Assets, Benefits Paid	0	(32)
Accrued pension cost	$ 0	$ 0
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	0.00%	2.50%
FPU Pension Plan
Components of net periodic cost:
Interest cost	$ 1,781	$ 1,714	2,085
Expected return on assets	(3,430)	(3,306)	(2,967)
Actuarial (gain) loss	466	612	552
Net periodic pension cost	(1,183)	(980)	(330)
Amortization of pre-merger regulatory asset	0	0	0
Net periodic postretirement cost	$ (1,183)	$ (980)	$ (330)
Assumptions
Discount rate	2.75%	2.50%	3.25%
Expected return on plan assets	6.00%	6.00%	6.00%
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ (15,713)	$ (1,953)
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(3,157)	(3,097)
Defined Benefit Plan, Plan Assets, Amount	46,203	58,712	$ 55,966
Defined Benefit Plan, Plan Assets, Contributions by Employer	200	1,597
Defined Benefit Plan, Plan Assets, Benefits Paid	(3,157)	(3,097)
Accrued pension cost	$ (3,738)	$ (8,318)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	5.25%	2.75%