Utility Regulatory Assets and Liabilities and Regulatory Matters - Narrative (Details) - USD ($) $ in Millions																12 Months Ended
	Jul. 31, 2024	Apr. 11, 2024	Dec. 21, 2023	Oct. 06, 2023	Oct. 01, 2023	Sep. 21, 2023	Jul. 31, 2023	Mar. 06, 2023	Jan. 27, 2023	Nov. 16, 2022	Nov. 01, 2022	Oct. 29, 2022	Sep. 15, 2022	Jul. 29, 2022	Jan. 28, 2022	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Oct. 19, 2016
Regulatory Assets [Line Items]
Regulatory asset, amortization period																			20 years
Net gains (losses) on commodity derivative instruments not associated with current-period transactions																$ (10)	$ (1,682)	$ 648
Public Service Commission of West Virginia | Mountaineer | Weather Normalization Adjustment Rider
Regulatory Assets [Line Items]
Approved rate increase		2.00%
Public utilities, rate matters, approved period			5 years
Public utilities, approved rate increase (decrease), percentage threshold		2.00%
Public Service Commission of West Virginia | Mountaineer | 2024 Infrastructure Replacement And Expansion Plan Expected
Regulatory Assets [Line Items]
Requested rate increase (decrease)	$ 19
Capital investments increase (decrease)	197
Public Service Commission of West Virginia | Mountaineer | 2024 Infrastructure Replacement and Expansion Plan, Prior Year Under-recovery
Regulatory Assets [Line Items]
Requested rate increase (decrease)	3
Public Service Commission of West Virginia | Mountaineer | 2024 Infrastructure Replacement and Expansion Plan, Capital Investments 2025
Regulatory Assets [Line Items]
Capital investments increase (decrease)	74
Public Service Commission of West Virginia | Mountaineer | 2024 Infrastructure Replacement and Expansion Plan, Capital Improvements 2025 Through 2029
Regulatory Assets [Line Items]
Capital investments increase (decrease)	$ 418
Public Service Commission of West Virginia | Mountaineer | 2023 Infrastructure Replacement and Expansion Plan
Regulatory Assets [Line Items]
Requested rate increase (decrease)							$ 10
Public Service Commission of West Virginia | Mountaineer | 2023 Infrastructure Replacement and Expansion Plan, Requested Recovery
Regulatory Assets [Line Items]
Requested rate increase (decrease)							6
Public Service Commission of West Virginia | Mountaineer | 2023 Infrastructure Replacement and Expansion Plan, Capital Improvement 2023
Regulatory Assets [Line Items]
Costs associated with capital investments							131
Public Service Commission of West Virginia | Mountaineer | 2023 Infrastructure Replacement and Expansion Plan, Capital Improvements 2024
Regulatory Assets [Line Items]
Costs associated with capital investments							67
Public Service Commission of West Virginia | Mountaineer | 2023 Infrastructure Replacement and Expansion Plan, Expected
Regulatory Assets [Line Items]
Capital investments increase (decrease)							(12)
Public Service Commission of West Virginia | Mountaineer | 2023 Infrastructure Replacement and Expansion Plan, Capital Investments
Regulatory Assets [Line Items]
Requested rate increase (decrease)							$ 383
Public Service Commission of West Virginia | Mountaineer | Net Revenue Increase
Regulatory Assets [Line Items]
Requested rate increase (decrease)				$ 14				$ 20
Public Service Commission of West Virginia | Mountaineer | Base Rate Case, Base Rate
Regulatory Assets [Line Items]
Requested rate increase (decrease)								38
Public Service Commission of West Virginia | Mountaineer | Base Rate Case, Infrastructure Rider
Regulatory Assets [Line Items]
Requested rate increase (decrease)								$ (18)
Public Service Commission of West Virginia | Mountaineer | 2022 IREP For 2023 - 2027
Regulatory Assets [Line Items]
Requested rate increase (decrease)														$ 354
Public Service Commission of West Virginia | Mountaineer | 2022 IREP For 2023
Regulatory Assets [Line Items]
Requested rate increase (decrease)														$ 64
Public Service Commission of West Virginia | Mountaineer | 2023 IREP Revenue
Regulatory Assets [Line Items]
Requested rate increase (decrease)										$ 22
Public Service Commission of West Virginia | Mountaineer | 2021 IREP Recovery
Regulatory Assets [Line Items]
Requested rate increase (decrease)										$ 1
Pennsylvania Public Utility Commission | UGI Utilities, Inc.
Regulatory Assets [Line Items]
Requested rate increase (decrease)									$ 11
Approved rate increase, amount						$ 9
Pennsylvania Public Utility Commission | Regulated natural gas utilities
Regulatory Assets [Line Items]
Requested rate increase (decrease)															$ 83
Pennsylvania Public Utility Commission | Regulated natural gas utilities | Joint Petition for Approval of Settlement
Regulatory Assets [Line Items]
Approved rate increase, amount													$ 49
Public utilities											5 years
Approved rate increase											3.00%
Property, plant and equipment, net threshold													$ 3,368
Pennsylvania Public Utility Commission | Regulated natural gas utilities | Joint Petition for Approval of Settlement, Phase I
Regulatory Assets [Line Items]
Approved rate increase, amount												$ 38
Pennsylvania Public Utility Commission | Regulated natural gas utilities | Joint Petition for Approval of Settlement, Phase II
Regulatory Assets [Line Items]
Approved rate increase, amount					$ 11
Pennsylvania Public Utility Commission | Regulated natural gas utilities | Weather Normalization Adjustment Rider
Regulatory Assets [Line Items]
Approved rate increase											3.00%
Postretirement benefits
Regulatory Assets [Line Items]
Regulatory liability, amortization period																			10 years
Regulated natural gas utilities
Regulatory Assets [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions																$ 2	$ (2)
Minimum
Regulatory Assets [Line Items]
Average remaining depreciable lives of associated property																1 year
Maximum
Regulatory Assets [Line Items]
Average remaining depreciable lives of associated property																65 years
Maximum | Removal Costs, Net
Regulatory Assets [Line Items]
Regulatory asset, amortization period																5 years