Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 201.9	$ 192.8	$ 555.0	$ 491.5
Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	164.3	151.8	413.6	351.4
Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	45.2	47.9	158.9	154.6
Other Businesses and Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(7.6)	(6.9)	(17.5)	(14.5)
Energy distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	150.4	138.5	385.0	324.2
Energy distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	150.4	138.5	385.0	324.2
Energy distribution \| Delaware natural gas distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	19.9	15.5	74.0	57.8
Energy distribution \| Delaware natural gas distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	19.9	15.5	74.0	57.8
Energy distribution \| FPU natural gas distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	50.1	46.6	109.0	97.9
Energy distribution \| FPU natural gas distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	50.1	46.6	109.0	97.9
Energy distribution \| Florida City Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	41.9	39.5	107.4	83.1
Energy distribution \| Florida City Gas \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	41.9	39.5	107.4	83.1
Energy distribution \| FPU electric distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	26.5	26.2	54.2	49.4
Energy distribution \| FPU electric distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	26.5	26.2	54.2	49.4
Energy distribution \| Maryland natural gas distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	12.0	10.7	40.4	36.0
Energy distribution \| Maryland natural gas distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	12.0	10.7	40.4	36.0
Energy transmission
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	46.5	41.7	114.1	94.0
Energy transmission \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	39.4	33.3	80.7	66.4
Energy transmission \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7.1	8.4	33.4	27.6
Energy transmission \| Aspire Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7.1	8.4	33.4	27.6
Energy transmission \| Aspire Energy \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7.1	8.4	33.4	27.6
Energy transmission \| Aspire Energy Express
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.4	0.3	0.7	0.7
Energy transmission \| Aspire Energy Express \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.4	0.3	0.7	0.7
Energy transmission \| Eastern Shore
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	22.4	21.2	46.6	43.9
Energy transmission \| Eastern Shore \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	22.4	21.2	46.6	43.9
Energy transmission \| Peninsula Pipeline
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16.6	11.8	33.4	21.8
Energy transmission \| Peninsula Pipeline \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16.6	11.8	33.4	21.8
Energy generation \| Eight Flags
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5.0	4.6	10.9	9.3
Energy generation \| Eight Flags \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5.0	4.6	10.9	9.3
Propane operations \| Propane delivery operations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	26.3	26.5	99.6	101.2
Propane operations \| Propane delivery operations \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	26.3	26.5	99.6	101.2
CNG / RNG Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7.0	8.4	15.2	16.6
CNG / RNG Services \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7.0	8.4	15.2	16.6
CNG / RNG Services \| Marlin Gas Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5.7	7.3	13.2	14.5
CNG / RNG Services \| Marlin Gas Services \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5.7	7.3	13.2	14.5
CNG / RNG Services \| Other RNG
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1.3	1.1	2.0	2.1
CNG / RNG Services \| Other RNG \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1.3	1.1	2.0	2.1
Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(33.3)	(26.9)	(69.8)	(53.8)
Eliminations \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(25.5)	(20.0)	(52.1)	(39.2)
Eliminations \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(0.2)	0.0	(0.2)	(0.1)
Eliminations \| Other Businesses and Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ (7.6)	$ (6.9)	$ (17.5)	$ (14.5)