Derivative Instruments and Hedging Activities - Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	$ 253	$ 246	$ 501	$ 487
Other Income (Expense) - net	76	131	201	183
Cash Flow Hedges [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (Loss) Reclassified from AOCI into Income	24	33	27	3
Cash Flow Hedges [Member] | Other Comprehensive Income (Loss) [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Derivative Gain (Loss) Recognized in OCI	34	43	44	20
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	(5)	(8)	(10)	(8)
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	(2)	(2)	(5)	(4)
Amount of gain (loss) reclassified from AOCI to income	(2)		(5)
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Other Income (Expense) Net [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Amount of gain (loss) reclassified from AOCI to income	0		0
Cash Flow Hedges [Member] | Cross Currency Swaps [Member] | Other Comprehensive Income (Loss) [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Derivative Gain (Loss) Recognized in OCI	39	51	54	28
Cash Flow Hedges [Member] | Cross Currency Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Amount of gain (loss) reclassified from AOCI to income	0		0
Hedged items	0		0
Cash Flow Hedges [Member] | Cross Currency Swaps [Member] | Other Income (Expense) Net [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (Loss) Reclassified from AOCI into Income	26	35	32	7
Amount of gain (loss) reclassified from AOCI to income	26		32
Hedged items	(26)		(32)
Net Investment Hedges [Member] | Foreign Currency Contracts [Member] | Other Comprehensive Income (Loss) [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Derivative Gain (Loss) Recognized in OCI	1	1	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	(1)	44	60	10
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)	(7)	(3)
Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	(2)	(1)	(3)	(2)
Not Designated As Hedging Instruments [Member] | Foreign Currency Contracts [Member] | Other Income (Expense) Net [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	1	45	63	12
LG And E And KU Energy LLC [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	58	58	116	112
Other Income (Expense) - net	2	0	2	0
LG And E And KU Energy LLC [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)	(7)	(3)
LG And E And KU Energy LLC [Member] | Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	(2)	(1)	(3)	(2)
Louisville Gas And Electric Co [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	22	22	44	43
Other Income (Expense) - net	1	(1)	0	(1)
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)	(7)	(3)
Louisville Gas And Electric Co [Member] | Not Designated As Hedging Instruments [Member] | Interest Rate Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	(2)	(1)	(3)	(2)
Kentucky Utilities Co [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	29	28	57	54
Other Income (Expense) - net	$ 0	$ (2)	$ 1	$ 0