Rates and Other Regulatory Activities Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets		$ 101.3	$ 115.9
Regulatory Liabilities		200.1	209.0
Overrecovered Gas And Fuel Costs [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	[1]	15.5	12.3
Storm Reserve [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	[2]	2.1	1.9
Accrued asset removal cost
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	[3]	77.9	86.5
Deferred Income Tax Due to Rate Change [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities	[4]	102.6	105.1
Other Regulatory Liability [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Liabilities		2.0	3.2
Underrecovered Gas And Fuel Costs [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets	[1],[5]	9.7	13.7
Deferred Post Retirement Benefits [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets	[6]	7.7	10.8
Deferred Conversion And Development Costs [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets	[1]	20.6	21.5
Acquisition Adjustment [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets	[7]	29.6	31.9
Other Regulatory Asset [Member]
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets		19.8	15.6
Deferred Storm Costs
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets	[8]	11.1	19.4
Under-recovered GRIP Revenues
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets	[9]	1.6	1.8
Deferred rate case expenses - current
Rates and Other Regulatory Activities [Line Items]
Regulatory Assets		1.2	$ 1.2
Florida Public Utilities Company [Member]
Rates and Other Regulatory Activities [Line Items]
Business Acquisition Premium Paid		34.2
Indiantown Gas Company
Rates and Other Regulatory Activities [Line Items]
Business Acquisition Premium Paid		$ 0.7

[1] We are allowed to recover the asset or are required to pay the liability in rates. We do not earn an overall rate of return on these assets.

[2] We have storm reserves in our Florida regulated energy operations that allow us to collect through rates amounts to be used against general claims, storm restoration costs and other losses as they are incurred.

[3] See Note 2, Summary of Significant Accounting Policies, for additional information on our asset removal cost policies.

[4] We recorded a regulatory liability for our regulated businesses related to the revaluation of accumulated deferred tax assets/liabilities as a result of the TCJA. The liability will be amortized over a period between 5 to 80 years based on the remaining life of the associated property. Based upon the regulatory proceedings, we will pass back the respective portion of the excess accumulated deferred taxes to rate payers. See Note 11, Income Taxes, for additional information.

[5] Includes amounts being recovered over a three-year period primarily concentrated in our electric division. Per Florida PSC approval, our electric division was allowed to recover these amounts over an extended period of time in an effort to reduce the impact of increased commodity prices to our customers. Recovery of these costs began in January 2023.

[6] The Florida PSC allowed FPU to treat as a regulatory asset the portion of the unrecognized costs pursuant to ASC Topic 715, Compensation - Retirement Benefits, related to its regulated operations. This balance also includes the portion of pension settlement expense associated with the termination of the Chesapeake Pension Plan pursuant to an order from the FERC and the respective PSCs that allowed us to defer Eastern Shore, Delaware and Maryland Divisions' portion. See Note 16, Employee Benefit Plans, for additional information.

[7] We are allowed to include the premiums paid in various natural gas utility acquisitions in Florida in our rate bases and recover them over a specific time period pursuant to the Florida PSC approvals. We paid $34.2 million of the premium in 2009, including a gross up for income tax, because it is not tax deductible, and $0.7 million of the premium paid by FPU in 2010. For additional information, see Florida Natural Gas Rate Case discussion above.

[8] The Florida PSC authorized us to recover regulatory assets (including interest) associated with the recovery of Hurricanes Michael and Dorian storm costs which will be amortized between 6 and 10 years. Recovery of these costs includes a component of an overall return on capital additions and regulatory assets.

[9] The Florida PSC allowed us to recover through a surcharge, capital and other program-related-costs, inclusive of an appropriate return on investment, associated with accelerating the replacement of qualifying gas distribution mains and services (defined as any material other than coated steel or plastic) in FPU’s natural gas distribution operations, Fort Meade division and Chesapeake Utilities’ CFG division. We are allowed to recover the asset or are required to pay the liability in rates related to GRIP.