Derivative Instruments and Hedging Activities (Gains and Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flow Hedges [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) reclassified from AOCI into income on derivative (effective portion)	$ 53	$ 85	$ 163
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	(70)	2	1
Cash Flow Hedges [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	26	(33)	86
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	(34)	(91)	127
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 on derivative (effective portion)	(11)	(18)	(20)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0	2	0
Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Discontinued Operations [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	0
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	(77)
Cash Flow Hedges [Member] | Cross Currency Swaps [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	60	58	(41)
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 on derivative (effective portion)	2	4	1
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	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 on derivative (effective portion)	49	57	(28)
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	0	0	0
Net Investment Hedges [Member] | Foreign Currency Contracts [Member] | Other Comprehensive Income [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in OCI on derivative (effective portion)	9	23	(14)
Derivatives 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	(22)	(66)	0
Derivatives Designated As Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Regulatory Liabilities Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets	0	0	72
Derivatives Designated As Hedging Instruments [Member] | 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 on derivative (effective portion)	13	42	210
Gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	7	0	1
Derivatives Not Designated As Hedging Instruments [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized in income on derivative	114	113	(46)
Derivatives 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	(12)	22
Derivatives 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	(8)	(8)	(8)
Derivatives 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	122	121	(38)
LG And E And KU Energy LLC [Member] | Derivatives 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	(22)	(66)	0
LG And E And KU Energy LLC [Member] | Derivatives Designated As Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Regulatory Liabilities Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets	0	0	72
LG And E And KU Energy LLC [Member] | Derivatives Not 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	1	(12)	22
LG And E And KU Energy LLC [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Cash Flow Hedges [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	(8)	(8)	(8)
Louisville Gas And Electric Co [Member] | Derivatives 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	(11)	(33)	0
Louisville Gas And Electric Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Regulatory Liabilities Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets	0	0	36
Louisville Gas And Electric Co [Member] | Derivatives Not 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	1	(12)	22
Louisville Gas And Electric Co [Member] | Derivatives Not Designated As Hedging Instruments [Member] | Cash Flow Hedges [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	(8)	(8)	(8)
Kentucky Utilities Co [Member] | Derivatives 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	(11)	(33)	0
Kentucky Utilities Co [Member] | Derivatives Designated As Hedging Instruments [Member] | Cash Flow Hedges [Member] | Interest Rate Swaps [Member] | Regulatory Liabilities Noncurrent [Member]
Amounts Included in Income, OCI or Regulatory Liabilities/Assets [Abstract]
Gain (loss) recognized as regulatory liabilities/assets	$ 0	$ 0	$ 36