Derivative Instruments and Hedging Activities - Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	$ 249	$ 259	$ 750	$ 746
Other Income (Expense) - net	52	126	253	309
Cash Flow Hedges [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (Loss) Reclassified from AOCI into Income	(60)	25	(33)	28
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	(64)	19	(20)	39
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	3	(22)	(7)	(30)
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	(4)	(2)	(9)	(6)
Amount of gain (loss) reclassified from AOCI to income	(4)	(2)	(9)	(6)
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	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	(67)	41	(13)	69
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	0	0
Hedged items	0	0	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	(56)	27	(24)	34
Amount of gain (loss) reclassified from AOCI to income	(56)	27	(24)	34
Hedged items	56	(27)	24	(34)
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	0	0	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	(20)	43	40	53
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	2	(2)	(5)	(5)
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	(1)	(1)	(4)	(3)
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	(19)	44	44	56
LG And E And KU Energy LLC [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	56	57	172	169
Other Income (Expense) - net	1	2	3	2
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	2	(2)	(5)	(5)
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	(1)	(1)	(4)	(3)
Louisville Gas And Electric Co [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	22	22	66	65
Other Income (Expense) - net	(1)	0	(1)	(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	2	(2)	(5)	(5)
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	(1)	(1)	(4)	(3)
Kentucky Utilities Co [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Expense	28	28	85	82
Other Income (Expense) - net	$ 1	$ 4	$ 2	$ 4