Derivative Instruments and Hedging Activities - Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	$ 190	$ 179
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Other Income (Expense) - net	28	22
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Other Comprehensive Income (Loss) [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Derivative Gain (Loss) Recognized in OCI		0
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (Loss) Reclassified from AOCI into Income	(1)	(1)
Amount of gain (loss) reclassified from AOCI to income	(1)	(1)
Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	(5)	(16)
Gain (loss) recognized as regulatory liabilities/assets	18	28
Asset value	22		$ 9
Liability value	11		16
Not Designated As Hedging Instruments [Member] | Other Noncurrent Assets [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Asset value	6		2
Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Noncurrent Assets [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Asset value	0		0
Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Regulatory Assets Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets	(1)	2
Not Designated As Hedging Instruments [Member] | Gas Contracts
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	$ (5)	$ (16)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Energy purchases	Energy purchases
Not Designated As Hedging Instruments [Member] | Gas Contracts | Regulatory Assets Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets	$ 1
Not Designated As Hedging Instruments [Member] | Gas Contracts | Regulatory Assets, current
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets	18
Not Designated As Hedging Instruments [Member] | Gas Contract | Other Noncurrent Assets [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Asset value	6		2
Not Designated As Hedging Instruments [Member] | Gas Contract | Regulatory Assets Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets		$ 4
Not Designated As Hedging Instruments [Member] | Gas Contract | Regulatory Assets, current
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets		22
Louisville Gas And Electric Co [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	26	26
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Other Income (Expense) - net	3	2
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Asset value	0		0
Liability value	5		3
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Other Noncurrent Assets [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Asset value	0		0
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Price risk management liabilities, current
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Liability value	1		0
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Price risk management, liabilities, noncurrent
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Liability value	4		3
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	$ 0	$ 0
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest Expense	Interest Expense
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Noncurrent Assets [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Asset value	$ 0		0
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Price risk management liabilities, current
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Liability value	1		0
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Price risk management, liabilities, noncurrent
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Liability value			$ 3
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Regulatory Assets Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets	(1)	$ 2
Kentucky Utilities Co [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	35	34
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Other Income (Expense) - net	$ 5	$ 2