Financing Activities (Long-term Debt and Equity Securities) (Details) shares in Thousands, £ in Millions, $ in Millions	1 Months Ended											3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Nov. 30, 2017 GBP (£)	Oct. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Aug. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	May 31, 2017 USD ($)	Apr. 30, 2017 USD ($)	Mar. 31, 2016	Feb. 28, 2015 USD ($) Integer	Mar. 31, 2017 USD ($)	Mar. 31, 2017 GBP (£)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Jan. 31, 2018 USD ($)	Dec. 31, 2017 GBP (£)	Dec. 31, 2016 GBP (£)
Debt Instrument [Line Items]
Principal outstanding	$ 20,282														$ 20,282	$ 18,399
Less current portion of Long-term debt	348														348	518
Long-term Debt	19,847														19,847	17,808
Aggregate maturities of long-term debt (Details) [Abstract]
2018	348														348
2019	430														430
2020	1,278														1,278
2021	1,150														1,150
2022	1,274														1,274
Thereafter	15,802														15,802
Equity Programs (Numeric) [Abstract]
Net proceeds from issuance of common stock															$ 453	144	$ 203
WPD [Member] | Senior Secured Notes [Member]
Debt Instrument [Line Items]
Repayments of Senior Debt	$ 100
Long-term Debt (Numeric) [Abstract]
Stated interest rate	7.25%														7.25%				7.25%
WPD South West [Member] | Senior Secured Notes [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount		$ 250
Stated interest rate		2.375%
Maturity date (in years)		Dec. 31, 2029	Dec. 31, 2029
Proceeds from debt, including premium net of debt issuance costs		$ 326	£ 247
WPD South West [Member] | Index Linked Senior Unsecured Notes [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount that may be redeemed in total by series	$ 304														$ 304				£ 225
Earliest date the company may redeem the debt in total by series															Dec. 01, 2026
Increase (decrease) in principal due to inflation	37														$ 37				27
WPD South Wales [Member] | Index Linked Senior Unsecured Notes [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount | £													£ 50
Stated interest rate													0.01%
Maturity date (in years)												Dec. 31, 2029	Dec. 31, 2029
Proceeds from Debt, Net of Issuance Costs | £													£ 53
Proceeds from debt, including premium net of debt issuance costs												$ 64
Increase (decrease) in principal due to inflation	37														37				27
WPD East Midlands [Member] | Index Linked Senior Unsecured Notes [Member]
Long-term Debt (Numeric) [Abstract]
Increase (decrease) in principal due to inflation	37														37				£ 27
PPL Capital Funding [Member] | Senior Secured Notes [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount					$ 500									$ 500
Stated interest rate					4.00%									4.00%
Maturity date (in years)														Dec. 31, 2047
Proceeds from debt, including premium net of debt issuance costs														$ 490
PPL Electric [Member] | Senior Secured Notes [Member] | Lehigh County Industrial Development Authority Pollution Control Revenue Refunding Bonds Series 2016B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount						$ 108
Stated interest rate						1.80%
Maturity date (in years)						Dec. 31, 2027
Debt Instruments Future Repurchase Date						Aug. 15, 2022
PPL Electric [Member] | Senior Secured Notes [Member] | Lehigh County Industrial Development Authority Pollution Control Revenue Refunding Bonds Series 2016A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount					$ 116									$ 116
Stated interest rate					1.80%									1.80%
Maturity date (in years)					Dec. 31, 2029
Debt Instruments Future Repurchase Date					Sep. 01, 2022
PPL Electric [Member] | Senior Secured Notes - First Mortgage Bonds [Member] | Mortgage Indenture [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate carrying value of property subject to lien	8,500														8,500	7,600
PPL Electric [Member] | Senior Secured Notes - First Mortgage Bonds [Member] | Pollution Control Revenue Refunding Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount that may be redeemed at a future date	224														224
Principal amount that may be redeemed in whole or in part	90														$ 90
Earliest date the company may redeem the debt in whole or in part															Oct. 31, 2020
Minimum length of time to convert interest rate mode															1 year
PPL Electric [Member] | First Mortgage Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount								$ 475
Stated interest rate								3.95%
Maturity date (in years)								Dec. 31, 2047
Proceeds from Debt, Net of Issuance Costs								$ 466
LGE [Member]
Long-term Debt (Numeric) [Abstract]
Capacity	700														$ 700
Borrowed	$ 100														$ 100	0
LGE [Member] | Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Expiration date				Oct. 31, 2019											Oct. 31, 2019
Interest rate on outstanding borrowing	2.06%														2.06%				2.06%
Long-term Debt (Numeric) [Abstract]
Capacity	$ 200			$ 200											$ 200
Borrowed	100														100	0
LGE [Member] | Term Loan Credit Facility [Member] | Subsequent Event [Member]
Long-term Debt (Numeric) [Abstract]
Borrowed																		$ 100
LGE [Member] | Senior Secured Notes [Member] | Pollution Control Revenue Bonds, 2003 Series A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount									$ 128
Stated interest rate									1.50%
Maturity date (in years)									Dec. 31, 2033
Debt Instruments Future Repurchase Date									Apr. 01, 2019
LGE [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2017 Series A [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 60
Stated interest rate							3.75%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 01, 2027
LGE [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series A [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 60
Maturity date (in years)							Dec. 31, 2033
LGE [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 31
Stated interest rate							1.25%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 03, 2019
LGE [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 35
Stated interest rate							1.25%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 03, 2019
LGE [Member] | Senior Secured Notes [Member] | Louisville/Jefferson County Metro Government Environmental Facilities Revenue Bonds 2001 Series A [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount		$ 10
Maturity date (in years)		Dec. 31, 2027	Dec. 31, 2027
LGE [Member] | First Mortgage Bonds [Member] | 2010 Mortgage Indenture [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate carrying value of property subject to lien	4,700														$ 4,700	4,400
LGE [Member] | First Mortgage Bonds [Member] | Tax Exempt Revenue Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Minimum length of time to convert interest rate mode															1 year
LKE [Member] | First Mortgage Bonds [Member] | Tax Exempt Revenue Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate amount of tax-exempt revenue bonds in a term rate mode	514														$ 514
Aggregate amount of tax-exempt revenue bonds in a variable rate mode	375														375
KU [Member]
Long-term Debt (Numeric) [Abstract]
Capacity	598														598
Borrowed	0														0	0
KU [Member] | First Mortgage Bonds [Member] | 2010 Mortgage Indenture [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate carrying value of property subject to lien	6,000														$ 6,000	$ 5,800
KU [Member] | First Mortgage Bonds [Member] | Tax Exempt Revenue Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Minimum length of time to convert interest rate mode															1 year
At The Market Stock Offering Program [Member]
Equity Programs (Numeric) [Abstract]
Shares of common stock issued during the period | shares															10,373	710	1,477
Net proceeds from issuance of common stock															$ 377	$ 25	$ 49
Maximum Percentage Paid To Selling Agents															1.00%
Number of distribution agreements | Integer											2
Aggregate sales price of common stock based on two separate equity distribution agreements											$ 500
U.S. [Member]
Debt Instrument [Line Items]
Principal outstanding	$ 12,919														$ 12,919	11,854
U.S. [Member] | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	3.78%														3.78%				3.78%
Maturity date of long-term debt range start															Dec. 31, 2020
Maturity date of long-term date range end															Dec. 31, 2047
Principal outstanding	$ 4,575														$ 4,575	4,075
U.S. [Member] | Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	2.06%														2.06%				2.06%
Maturity date of long-term date range end															Dec. 31, 2019
Principal outstanding	$ 100														$ 100	0
U.S. [Member] | Senior Secured Notes - First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	3.96%														3.96%				3.96%
Maturity date of long-term debt range start															Dec. 31, 2018
Maturity date of long-term date range end															Dec. 31, 2047
Principal outstanding	$ 7,314														$ 7,314	6,849
U.S. [Member] | Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	5.10%														5.10%				5.10%
Maturity date of long-term debt range start															Dec. 31, 2067
Maturity date of long-term date range end															Dec. 31, 2073
Principal outstanding	$ 930														$ 930	930
U.S. [Member] | PPL Capital Funding [Member]
Long-term Debt (Numeric) [Abstract]
Capacity	1,400														1,400
Borrowed	0														0	0
U.K. [Member]
Debt Instrument [Line Items]
Principal outstanding	7,363														7,363	6,545
Fair market value adjustments	21														21	22
Unamortized premium and (discount), net	14														14	20
Unamortized debt issuance costs	(122)														(122)	(115)
Total Long-term Debt	20,195														20,195	18,326
Less current portion of Long-term debt	348														348	518
Long-term Debt	19,847														19,847	17,808
Long-term Debt (Numeric) [Abstract]
Principal amount that may be put back to the issuer	$ 6,400														$ 6,400				£ 4,700
Capacity | £																			1,155
Borrowed | £																			£ 448	£ 339
U.K. [Member] | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	5.24%														5.24%				5.24%
Maturity date of long-term debt range start															Dec. 31, 2020
Maturity date of long-term date range end															Dec. 31, 2040
Principal outstanding	$ 6,351														$ 6,351	5,707
Long-term Debt (Numeric) [Abstract]
Principal amount that may be redeemed in total but not in part	$ 304														$ 304				£ 225
Earliest date the company may redeem the debt in total but not in part															Dec. 21, 2026
U.K. [Member] | Index Linked Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	1.56%														1.56%				1.56%
Maturity date of long-term debt range start															Dec. 31, 2026
Maturity date of long-term date range end															Dec. 31, 2056
Principal outstanding	$ 1,012														$ 1,012	838
PPL Electric Utilities Corp [Member]
Debt Instrument [Line Items]
Principal outstanding	3,339														3,339	2,864
Unamortized discount	(16)														(16)	(12)
Unamortized debt issuance costs	(25)														(25)	(21)
Total Long-term Debt	3,298														3,298	2,831
Less current portion of Long-term debt	0														0	224
Long-term Debt	3,298														3,298	2,607
Aggregate maturities of long-term debt (Details) [Abstract]
2018	0														0
2019	0														0
2020	100														100
2021	400														400
2022	474														474
Thereafter	$ 2,365														$ 2,365
PPL Electric Utilities Corp [Member] | Senior Secured Notes [Member] | Lehigh County Industrial Development Authority Pollution Control Revenue Refunding Bonds Series 2016B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount						$ 108
Stated interest rate						1.80%
Maturity date (in years)						Dec. 31, 2027
Debt Instruments Future Repurchase Date						Aug. 15, 2022
PPL Electric Utilities Corp [Member] | Senior Secured Notes [Member] | Lehigh County Industrial Development Authority Pollution Control Revenue Refunding Bonds Series 2016A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount					$ 116									$ 116
Stated interest rate					1.80%									1.80%
Maturity date (in years)					Dec. 31, 2029
Debt Instruments Future Repurchase Date					Sep. 01, 2022
PPL Electric Utilities Corp [Member] | Senior Secured Notes - First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	4.23%														4.23%				4.23%
Maturity date of long-term debt range start															Dec. 31, 2020
Maturity date of long-term date range end															Dec. 31, 2047
Principal outstanding	$ 3,339														$ 3,339	2,864
PPL Electric Utilities Corp [Member] | Senior Secured Notes - First Mortgage Bonds [Member] | Mortgage Indenture [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate carrying value of property subject to lien	8,500														8,500	7,600
PPL Electric Utilities Corp [Member] | Senior Secured Notes - First Mortgage Bonds [Member] | Pollution Control Revenue Refunding Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount that may be redeemed at a future date	224														224
Principal amount that may be redeemed in whole or in part	90														$ 90
Earliest date the company may redeem the debt in whole or in part															Oct. 31, 2020
Minimum length of time to convert interest rate mode															1 year
PPL Electric Utilities Corp [Member] | First Mortgage Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount								$ 475
Stated interest rate								3.95%
Maturity date (in years)										Dec. 31, 2047
Proceeds from Debt, Net of Issuance Costs								$ 466
LG And E And KU Energy LLC [Member]
Debt Instrument [Line Items]
Principal outstanding	5,200														$ 5,200	5,110
Fair market value adjustments	0														0	(1)
Unamortized discount	(14)														(14)	(15)
Unamortized debt issuance costs	(27)														(27)	(29)
Total Long-term Debt	5,159														5,159	5,065
Less current portion of Long-term debt	98														98	194
Long-term Debt	5,061														5,061	4,871
Aggregate maturities of long-term debt (Details) [Abstract]
2018	98														98
2019	430														430
2020	975														975
2021	250														250
2022	0														0
Thereafter	$ 3,447														$ 3,447
LG And E And KU Energy LLC [Member] | Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	3.97%														3.97%				3.97%
Maturity date of long-term debt range start															Dec. 31, 2020
Maturity date of long-term date range end															Dec. 31, 2021
Principal outstanding	$ 725														$ 725	725
LG And E And KU Energy LLC [Member] | Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	2.06%														2.06%				2.06%
Maturity date of long-term date range end															Dec. 31, 2019
Principal outstanding	$ 100														$ 100	0
LG And E And KU Energy LLC [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	3.73%														3.73%				3.73%
Maturity date of long-term debt range start															Dec. 31, 2018
Maturity date of long-term date range end															Dec. 31, 2045
Principal outstanding	$ 3,975														$ 3,975	3,985
LG And E And KU Energy LLC [Member] | First Mortgage Bonds [Member] | Tax Exempt Revenue Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate amount of tax-exempt revenue bonds in a term rate mode	514														514
Aggregate amount of tax-exempt revenue bonds in a variable rate mode	$ 375														$ 375
LG And E And KU Energy LLC [Member] | Note Payable [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	3.50%														3.50%				3.50%
Maturity date of long-term date range end															Dec. 31, 2026
Principal outstanding	$ 400														$ 400	400
LG And E And KU Energy LLC [Member] | LGE [Member]
Long-term Debt (Numeric) [Abstract]
Capacity	700														700
Borrowed	$ 100														$ 100	0
LG And E And KU Energy LLC [Member] | LGE [Member] | Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Expiration date				Oct. 31, 2019											Oct. 31, 2019
Interest rate on outstanding borrowing	2.06%														2.06%				2.06%
Long-term Debt (Numeric) [Abstract]
Capacity	$ 200			$ 200											$ 200
Borrowed	100														100	0
LG And E And KU Energy LLC [Member] | LGE [Member] | Term Loan Credit Facility [Member] | Subsequent Event [Member]
Long-term Debt (Numeric) [Abstract]
Borrowed																		100
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Secured Notes [Member] | Pollution Control Revenue Bonds, 2003 Series A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount									$ 128
Stated interest rate									1.50%
Maturity date (in years)									Dec. 31, 2033
Debt Instruments Future Repurchase Date									Apr. 01, 2019
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2017 Series A [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 60
Stated interest rate							3.75%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 01, 2027
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series A [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 60
Maturity date (in years)							Dec. 31, 2033
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 31
Stated interest rate							1.25%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 03, 2019
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 35
Stated interest rate							1.25%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 03, 2019
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Secured Notes [Member] | Louisville/Jefferson County Metro Government Environmental Facilities Revenue Bonds 2001 Series A [Member] [Domain]
Long-term Debt (Numeric) [Abstract]
Principal amount		$ 10
Maturity date (in years)		Dec. 31, 2027	Dec. 31, 2027
LG And E And KU Energy LLC [Member] | LGE [Member] | First Mortgage Bonds [Member] | 2010 Mortgage Indenture [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate carrying value of property subject to lien	4,700														$ 4,700	4,400
LG And E And KU Energy LLC [Member] | LGE [Member] | First Mortgage Bonds [Member] | Tax Exempt Revenue Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Minimum length of time to convert interest rate mode															1 year
LG And E And KU Energy LLC [Member] | KU [Member]
Long-term Debt (Numeric) [Abstract]
Capacity	598														$ 598
Borrowed	0														0	0
LG And E And KU Energy LLC [Member] | KU [Member] | First Mortgage Bonds [Member] | 2010 Mortgage Indenture [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate carrying value of property subject to lien	6,000														$ 6,000	5,800
LG And E And KU Energy LLC [Member] | KU [Member] | First Mortgage Bonds [Member] | Tax Exempt Revenue Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Minimum length of time to convert interest rate mode															1 year
Louisville Gas And Electric Co [Member]
Debt Instrument [Line Items]
Principal outstanding	1,724														$ 1,724	1,634
Fair market value adjustments	0														0	(1)
Unamortized discount	(4)														(4)	(4)
Unamortized debt issuance costs	(11)														(11)	(12)
Total Long-term Debt	1,709														1,709	1,617
Less current portion of Long-term debt	98														98	194
Long-term Debt	1,611														1,611	1,423
Long-term Debt (Numeric) [Abstract]
Capacity	700														700
Borrowed	100														100	0
Aggregate maturities of long-term debt (Details) [Abstract]
2018	98														98
2019	334														334
2020	0														0
2021	0														0
2022	0														0
Thereafter	$ 1,292														$ 1,292
Louisville Gas And Electric Co [Member] | Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Expiration date				Oct. 31, 2019											Oct. 31, 2019
Interest rate on outstanding borrowing	2.06%														2.06%				2.06%
Long-term Debt (Numeric) [Abstract]
Capacity	$ 200			$ 200											$ 200
Borrowed	$ 100														$ 100	0
Louisville Gas And Electric Co [Member] | Term Loan Credit Facility [Member] | Subsequent Event [Member]
Long-term Debt (Numeric) [Abstract]
Borrowed																		$ 100
Louisville Gas And Electric Co [Member] | Term Loan Credit Facility [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	2.06%														2.06%				2.06%
Maturity date of long-term date range end															Dec. 31, 2019
Principal outstanding	$ 100														$ 100	0
Louisville Gas And Electric Co [Member] | Senior Secured Notes [Member] | Pollution Control Revenue Bonds, 2003 Series A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount									$ 128
Stated interest rate									1.50%
Maturity date (in years)									Dec. 31, 2033
Debt Instruments Future Repurchase Date									Apr. 01, 2019
Louisville Gas And Electric Co [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2017 Series A [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 60
Stated interest rate							3.75%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 01, 2027
Louisville Gas And Electric Co [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series A [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 60
Maturity date (in years)							Dec. 31, 2033
Louisville Gas And Electric Co [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 31
Stated interest rate							1.25%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 03, 2019
Louisville Gas And Electric Co [Member] | Senior Secured Notes [Member] | Environmental Facilities Revenue Refunding Bonds, 2007 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount							$ 35
Stated interest rate							1.25%
Maturity date (in years)							Dec. 31, 2033
Debt Instruments Future Repurchase Date							Jun. 03, 2019
Louisville Gas And Electric Co [Member] | Senior Secured Notes [Member] | Louisville/Jefferson County Metro Government Environmental Facilities Revenue Bonds 2001 Series A [Member] [Domain]
Long-term Debt (Numeric) [Abstract]
Principal amount		$ 10
Maturity date (in years)		Dec. 31, 2027	Dec. 31, 2027
Louisville Gas And Electric Co [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	3.48%														3.48%				3.48%
Maturity date of long-term debt range start															Dec. 31, 2018
Maturity date of long-term date range end															Dec. 31, 2045
Principal outstanding	$ 1,624														$ 1,624	1,634
Louisville Gas And Electric Co [Member] | First Mortgage Bonds [Member] | 2010 Mortgage Indenture [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate carrying value of property subject to lien	4,700														$ 4,700	4,400
Louisville Gas And Electric Co [Member] | First Mortgage Bonds [Member] | Tax Exempt Revenue Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Minimum length of time to convert interest rate mode															1 year
Aggregate amount of tax-exempt revenue bonds in a term rate mode	391														$ 391
Aggregate amount of tax-exempt revenue bonds in a variable rate mode	147														147
Kentucky Utilities Co [Member]
Debt Instrument [Line Items]
Principal outstanding	2,351														2,351	2,351
Unamortized discount	(9)														(9)	(9)
Unamortized debt issuance costs	(14)														(14)	(15)
Total Long-term Debt	2,328														2,328	2,327
Less current portion of Long-term debt	0														0	0
Long-term Debt	2,328														2,328	2,327
Long-term Debt (Numeric) [Abstract]
Capacity	598														598
Borrowed	0														0	0
Aggregate maturities of long-term debt (Details) [Abstract]
2018	0														0
2019	96														96
2020	500														500
2021	0														0
2022	0														0
Thereafter	$ 1,755														$ 1,755
Kentucky Utilities Co [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Weighted-Average Rate	3.91%														3.91%				3.91%
Maturity date of long-term debt range start															Dec. 31, 2019
Maturity date of long-term date range end															Dec. 31, 2045
Principal outstanding	$ 2,351														$ 2,351	2,351
Kentucky Utilities Co [Member] | First Mortgage Bonds [Member] | 2010 Mortgage Indenture [Member]
Long-term Debt (Numeric) [Abstract]
Aggregate carrying value of property subject to lien	6,000														$ 6,000	$ 5,800
Kentucky Utilities Co [Member] | First Mortgage Bonds [Member] | Tax Exempt Revenue Bonds [Member]
Long-term Debt (Numeric) [Abstract]
Minimum length of time to convert interest rate mode															1 year
Aggregate amount of tax-exempt revenue bonds in a term rate mode	123														$ 123
Aggregate amount of tax-exempt revenue bonds in a variable rate mode	$ 228														$ 228