Employee Benefit Plans - Schedule of Amounts Not Yet Reflected in Net Periodic Benefit Cost and Included in Accumulated Other Comprehensive Income Loss or Regulatory Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 81	$ 50	$ 48
Accumulated other comprehensive loss pre-tax	(3,200)
Total unrecognized cost	(12,800)
FPU Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	2,495	1,781	1,714
Post-merger regulatory asset	(8,700)
Total unrecognized cost	(10,800)
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	2,670	3,430	3,306
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year	(407)	(466)	(612)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 232	$ (1,183)	$ (980)
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	5.25%	2.75%	2.50%
Expected return on plan assets	6.00%	6.00%	6.00%
Chesapeake SERP
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 81	$ 50
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year	(8)	(28)	$ (28)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 89	$ 78	$ 76
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	5.00%	2.50%	2.25%
Chesapeake Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Total unrecognized cost	$ (1,200)