Revenue Recognition Disaggregation of Revenue (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenues	$ 787,200,000		$ 670,600,000		$ 680,700,000
Revenue from Contract with Customer, Excluding Assessed Tax	787,200,000	[1]	670,600,000	[2]	680,700,000	[3]
Other And Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(24,600,000)	[1]	(26,100,000)	[2]	(29,500,000)	[3]
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	200,000		200,000		300,000
Other [Member] | Segment Reporting, Reconciling Item, Corporate Nonsegment
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	200,000		200,000		300,000
Energy Transmission [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	152,900,000		148,900,000		163,500,000
Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(91,400,000)		(85,700,000)		(84,900,000)
Eliminations [Member] | Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(24,800,000)		(26,300,000)		(29,800,000)
Regulated Energy
Disaggregation of Revenue [Line Items]
Revenues	583,400,000		473,600,000		429,400,000
Revenue from Contract with Customer, Excluding Assessed Tax	583,400,000	[1]	473,600,000	[2]	429,400,000	[3]
Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	532,000,000.0		421,000,000.0		376,900,000
Regulated Energy | Energy Transmission [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	117,700,000		111,800,000		107,300,000
Regulated Energy | Eliminations [Member] | Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(66,300,000)		(59,200,000)		(54,800,000)
Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenues	228,400,000		223,100,000		280,800,000
Revenue from Contract with Customer, Excluding Assessed Tax	228,400,000	[1]	223,100,000	[2]	280,800,000	[3]
Unregulated Energy | Energy Transmission [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	35,200,000		37,100,000		56,200,000
Unregulated Energy | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	17,600,000
Unregulated Energy | Eliminations [Member] | Consolidation, Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(300,000)		(200,000)		(300,000)
Other [Member] | Regulated Energy
Disaggregation of Revenue [Line Items]
Revenues	1,600,000		1,200,000		500,000
Other [Member] | Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenues	400,000				400,000
Florida Natural Gas Distribution [Member] | Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax					155,900,000
Delaware natural gas division [Member] | Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	76,900,000		83,900,000		82,200,000
FPU Electric Distribution [Member] | Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	92,600,000		99,500,000		81,700,000
Florida Public Utilities Company [Member] | Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	170,300,000		168,400,000
Maryland Natural Gas [Member] | Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	24,600,000		28,100,000		26,600,000
Sandpiper [Member] | Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	20,000,000.0		20,200,000		21,300,000
Aspire [Member] | Unregulated Energy | Energy Transmission [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	35,200,000		37,100,000		56,200,000
Eastern Shore Gas Company [Member] | Regulated Energy | Energy Transmission [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	81,700,000		79,900,000		78,600,000
Peninsula Pipeline [Member] | Regulated Energy | Energy Transmission [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	34,500,000		30,400,000		27,300,000
Eight Flags [Member] | Unregulated Energy | Energy Generation [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	18,000,000.0		19,200,000		25,300,000
Florida Propane [Member] | Unregulated Energy | Propane Delivery [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	157,900,000		154,700,000		188,400,000
Marlin Gas Services [Member] | Unregulated Energy | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	16,600,000		12,300,000		11,200,000
Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(91,200,000)		(85,500,000)		(84,600,000)
Eliminations [Member] | Other And Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(24,600,000)		(26,100,000)		(29,500,000)
Eliminations [Member] | Regulated Energy | Other And Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(66,300,000)		(59,200,000)		(54,800,000)
Eliminations [Member] | Unregulated Energy | Other And Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(300,000)		(200,000)		(300,000)
Aspire Energy Express | Regulated Energy | Energy Transmission [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,500,000		1,500,000		1,400,000
Elkton Gas [Member] | Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	7,300,000		8,800,000		$ 9,200,000
Florida City Gas | Regulated Energy | Energy Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	140,300,000		$ 12,100,000	[4]
Other RNG | Unregulated Energy | Energy Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,000,000.0

[1] Total operating revenues for the year ended December 31, 2024, include other revenue (revenues from sources other than contracts with customers) of $1.6 million and $0.4 million for our Regulated and Unregulated Energy segments, respectively. The sources of other revenues include revenue from alternative revenue programs related to revenue normalization for Maryland division and Sandpiper and late fees

[2] Total operating revenues for the year ended December 31, 2023, include other revenue (revenues from sources other than contracts with customers) of $1.2 million and $0.4 million for our Regulated and Unregulated Energy segments, respectively. The sources of other revenues include revenue from alternative revenue programs related to revenue normalization for Maryland division and Sandpiper and late fees

[3] (1) Total operating revenues for the year ended December 31, 2022, include other revenue (revenues from sources other than contracts with customers) of $0.5 million and $0.4 million for our Regulated and Unregulated Energy segments, respectively. The sources of other revenues include revenue from alternative revenue programs related to revenue normalization for Maryland division and Sandpiper and late fees

[4] Operating revenues for FCG include amounts from the acquisition date through December 31, 2023. For additional information on FCG's results, see Note 4, Acquisitions, and discussion under Item 7, Management's Discussion and Analysis of Financial Condition and Results of Operations.