Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 195.8	$ 179.6	$ 750.8	$ 671.1
Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	165.0	146.4	578.6	497.8
Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	37.8	40.7	196.7	195.3
Other Businesses and Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(7.0)	(7.5)	(24.5)	(22.0)
Energy distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	150.8	133.3	535.8	457.5
Energy distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	150.8	133.3	535.8	457.5
Energy distribution \| Delaware natural gas distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13.1	10.9	87.1	68.7
Energy distribution \| Delaware natural gas distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13.1	10.9	87.1	68.7
Energy distribution \| FPU natural gas distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	45.3	42.3	154.3	140.2
Energy distribution \| FPU natural gas distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	45.3	42.3	154.3	140.2
Energy distribution \| Florida City Gas
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	49.3	40.8	156.7	123.9
Energy distribution \| Florida City Gas \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	49.3	40.8	156.7	123.9
Energy distribution \| FPU electric distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	33.7	30.7	87.9	80.1
Energy distribution \| FPU electric distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	33.7	30.7	87.9	80.1
Energy distribution \| Maryland natural gas distribution
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	9.4	8.6	49.8	44.6
Energy distribution \| Maryland natural gas distribution \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	9.4	8.6	49.8	44.6
Energy transmission
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	45.1	41.7	159.2	135.7
Energy transmission \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	40.0	35.7	120.7	102.1
Energy transmission \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5.1	6.0	38.5	33.6
Energy transmission \| Aspire Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5.1	6.0	38.5	33.6
Energy transmission \| Aspire Energy \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5.1	6.0	38.5	33.6
Energy transmission \| Aspire Energy Express
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.4	0.4	1.1	1.1
Energy transmission \| Aspire Energy Express \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.4	0.4	1.1	1.1
Energy transmission \| Eastern Shore
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	22.1	20.7	68.7	64.6
Energy transmission \| Eastern Shore \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	22.1	20.7	68.7	64.6
Energy transmission \| Peninsula Pipeline
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	17.5	14.6	50.9	36.4
Energy transmission \| Peninsula Pipeline \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	17.5	14.6	50.9	36.4
Energy generation \| Eight Flags
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	4.5	4.9	15.4	14.2
Energy generation \| Eight Flags \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	4.5	4.9	15.4	14.2
Propane operations \| Propane delivery operations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	21.0	22.2	120.6	123.4
Propane operations \| Propane delivery operations \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	21.0	22.2	120.6	123.4
CNG / RNG Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7.2	7.7	22.4	24.3
CNG / RNG Services \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7.2	7.7	22.4	24.3
CNG / RNG Services \| Marlin Gas Services
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	6.1	6.7	19.3	21.2
CNG / RNG Services \| Marlin Gas Services \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	6.1	6.7	19.3	21.2
CNG / RNG Services \| Other RNG
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1.1	1.0	3.1	3.1
CNG / RNG Services \| Other RNG \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1.1	1.0	3.1	3.1
Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(32.8)	(30.2)	(102.6)	(84.0)
Eliminations \| Regulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(25.8)	(22.6)	(77.9)	(61.8)
Eliminations \| Unregulated Energy
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.0	(0.1)	(0.2)	(0.2)
Eliminations \| Other Businesses and Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ (7.0)	$ (7.5)	$ (24.5)	$ (22.0)