Derivative Instruments and Hedging Activities - Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Cash Flow Hedges [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) reclassified from AOCI into income (effective portion)	$ (106)	$ 19	$ (9)	$ 40
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0	(70)	0	(70)
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 (effective portion)	(107)	32	(12)	34
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 (effective portion)	(3)	17	(21)	(2)
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 (effective portion)	(2)	(3)	(3)	(7)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0	0	0	0
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Discontinued Operations [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) reclassified from AOCI into income (effective portion)		0		0
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)		(77)		(77)
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 (effective portion)	(104)	15	9	36
Cash Flow Hedges [Member] | Cross Currency Swaps [Member] | Interest Expense [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) reclassified from AOCI into income (effective portion)	(1)	1	0	2
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	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 (effective portion)	(103)	15	(6)	32
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0	0	0	0
Cash Flow Hedges [Member] | Commodity Contracts [Member] | Other Comprehensive Income (Loss) [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Derivative gain (loss) recognized in OCI (effective portion)		0		0
Cash Flow Hedges [Member] | Commodity Contracts [Member] | Discontinued Operations [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) reclassified from AOCI into income (effective portion)		6		13
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)		7		7
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 (effective portion)	1	(17)	4	(1)
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		76		20
Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	169	(104)	227	(18)
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	(3)	7	(9)	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)	(2)	(4)	(4)
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	171	(102)	231	(14)
LG And E And KU Energy LLC [Member] | Designated As Hedging Instruments [Member] | Cash Flow Hedges [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		76		20
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	(3)	7	(9)	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)	(2)	(4)	(4)
Louisville Gas And Electric Co [Member] | Designated As Hedging Instruments [Member] | Cash Flow Hedges [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		38		10
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	(3)	7	(9)	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)	(2)	$ (4)	(4)
Kentucky Utilities Co [Member] | Designated As Hedging Instruments [Member] | Cash Flow Hedges [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		$ 38		$ 10