Revenue Recognition Disegragation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenue [Line Items]
Revenues		$ 298.7	$ 245.7
Revenue from Contract with Customer, Excluding Assessed Tax	[1]	298.7	245.7
Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenues		199.6	168.4
Revenue from Contract with Customer, Excluding Assessed Tax	[1]	199.6	168.4
Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenues		106.7	83.1
Revenue from Contract with Customer, Excluding Assessed Tax	[1]	106.7	83.1
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[1]	(7.6)	(5.8)
Other [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenues		(0.5)	0.6
Other [Member] | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenues		0.1	0.1
Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		185.7	155.5
Energy Distribution [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		185.7	155.5
Energy Distribution [Member] | Delaware natural gas division [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		42.3	31.9
Energy Distribution [Member] | Delaware natural gas division [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		42.3	31.9
Energy Distribution [Member] | FPU Electric Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		23.2	20.0
Energy Distribution [Member] | FPU Electric Distribution [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		23.2	20.0
Energy Distribution [Member] | Florida Public Utilities Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		51.3	47.9
Energy Distribution [Member] | Florida Public Utilities Company [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		51.3	47.9
Energy Distribution [Member] | Maryland Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	12.9	9.9
Energy Distribution [Member] | Maryland Natural Gas [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	12.9	9.9
Energy Distribution [Member] | Sandpiper [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	8.4	7.0
Energy Distribution [Member] | Sandpiper [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	8.4	7.0
Energy Distribution [Member] | Elkton Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	4.0
Energy Distribution [Member] | Elkton Gas [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	[2]	4.0	2.9
Energy Distribution [Member] | Florida City Gas | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		43.6	35.9
Energy Transmission [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		52.3	43.2
Energy Transmission [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		33.1	29.6
Energy Transmission [Member] | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		19.2	13.6
Energy Transmission [Member] | Aspire [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		19.2	13.6
Energy Transmission [Member] | Aspire [Member] | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		19.2	13.6
Energy Transmission [Member] | Eastern Shore Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		22.7	21.2
Energy Transmission [Member] | Eastern Shore Gas Company [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		22.7	21.2
Energy Transmission [Member] | Peninsula Pipeline [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		10.0	8.0
Energy Transmission [Member] | Peninsula Pipeline [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		10.0	8.0
Energy Transmission [Member] | Aspire Energy Express | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0.4	0.4
Energy Generation [Member] | Eight Flags [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4.7	4.6
Energy Generation [Member] | Eight Flags [Member] | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		4.7	4.6
Propane Delivery [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		74.7	61.6
Propane Delivery [Member] | Florida Propane | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		74.7	61.6
Energy Services [Member] | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		8.2	3.4
Energy Services [Member] | Marlin Gas Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		7.2
Energy Services [Member] | Marlin Gas Services [Member] | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			3.4
Energy Services [Member] | Other RNG | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		1.0
Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		(26.9)	(22.6)
Eliminations [Member] | Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		(19.2)	(16.7)
Eliminations [Member] | Unregulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		(0.1)	(0.1)
Eliminations [Member] | Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ (7.6)	$ (5.8)

[1] (2) Total operating revenues for the three months ended March 31, 2025 include other revenue (revenues from sources other than contracts with customers) of $0.5 million loss and $0.1 million for our Regulated Energy and Unregulated Energy segments, respectively, and $0.6 million and $0.1 million for our Regulated Energy and Unregulated Energy segments, respectively, for the three months ended March 31, 2024. The sources of other revenues include revenue from alternative revenue programs related to revenue normalization for the Maryland division and Sandpiper Energy and late fees

[2] (1) In accordance with the Maryland PSC approval of our natural gas base rate proceeding, effective April 2025, our natural gas distribution businesses in Maryland (Maryland natural gas division, Sandpiper natural gas/propane operations and Elkton Gas) will be consolidated for rate-making and other purposes and will be presented in a consolidated basis consistent with the final rate order going forward.