Utility Rate Regulation - Regulatory Matters (Details) - USD ($) $ in Millions						1 Months Ended	9 Months Ended
	Sep. 28, 2018	Jun. 14, 2018	Mar. 28, 2018	Mar. 20, 2018	Jan. 10, 2018	Aug. 31, 2016	Sep. 30, 2018	May 17, 2018
Pennsylvania Public Utility Commission [Member] | Remaining [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		$ 33
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		33
PPL Electric [Member] | Pennsylvania Public Utility Commission [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		$ 72
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Negative Surcharge								0.56%
Amended Negative Surcharge		7.05%
Approved Amount Of Rate Reduction Due To TCJA		$ 72
PPL Electric [Member] | Pennsylvania Public Utility Commission [Member] | Current [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		39
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		39
LKE [Member]
Regulatory Matters - Federal Matters - FERC Transmission Rate Filing [Abstract]
Transmission Expenses Mitigated For Certain Customers							$ 22
LKE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Additional Amount Of Rate Reduction Due To TCJA			$ 27
Approved Additional Amount Of Rate Reduction Due To TCJA	$ 13
LGE [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage	10.42%
LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 35
Public Utilities, Requested Rate Increase (Decrease), Percentage	3.00%
Regulatory Matters - Kentucky Activities - CPCN and ECR Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service					$ 166
LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			79
Approved Amount Of Rate Reduction Due To TCJA	$ 74
Interim Rate Reduction Due To TCJA, Amount			69
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	74
LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Existing Rate Mechanism [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			20
Approved Amount Of Rate Reduction Due To TCJA	20
Interim Rate Reduction Due To TCJA, Amount			20
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	20
LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			59
Approved Amount Of Rate Reduction Due To TCJA	54
Interim Rate Reduction Due To TCJA, Amount			49
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	54
LGE [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 25
Public Utilities, Requested Rate Increase (Decrease), Percentage	7.50%
LGE [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member] | Substantially All Through Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	$ 16
Interim Rate Reduction Due To TCJA, Amount			17
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	$ 16
KU [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage	10.42%
KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 112
Public Utilities, Requested Rate Increase (Decrease), Percentage	6.90%
Regulatory Matters - Kentucky Activities - CPCN and ECR Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service					155
KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			108
Approved Amount Of Rate Reduction Due To TCJA	$ 101
Interim Rate Reduction Due To TCJA, Amount			91
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	101
KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Existing Rate Mechanism [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			21
Approved Amount Of Rate Reduction Due To TCJA	21
Interim Rate Reduction Due To TCJA, Amount			21
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	21
KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			87
Approved Amount Of Rate Reduction Due To TCJA	80
Interim Rate Reduction Due To TCJA, Amount			70
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	80
PPL Electric Utilities Corp [Member] | Pennsylvania Public Utility Commission [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		$ 72
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Negative Surcharge								0.56%
Amended Negative Surcharge		7.05%
Approved Amount Of Rate Reduction Due To TCJA		$ 72
PPL Electric Utilities Corp [Member] | Pennsylvania Public Utility Commission [Member] | Current [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		39
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		39
PPL Electric Utilities Corp [Member] | Pennsylvania Public Utility Commission [Member] | Remaining [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		33
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA		$ 33
LG And E And KU Energy LLC [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Additional Amount Of Rate Reduction Due To TCJA			27
Approved Additional Amount Of Rate Reduction Due To TCJA	$ 13
LG And E And KU Energy LLC [Member] | LGE [Member]
Regulatory Matters - Kentucky Activities - Gas Franchise (Numeric) [Abstract]
Franchise Agreement Term						5 years
Days of Notice to Modify Franchise Fee						60 days
Franchise Fee Cap						3.00%
Franchise Fee If Recovered From Customers						0.00%
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage	10.42%
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 35
Public Utilities, Requested Rate Increase (Decrease), Percentage	3.00%
Regulatory Matters - Kentucky Activities - CPCN and ECR Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service					166
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			79
Approved Amount Of Rate Reduction Due To TCJA	$ 74
Interim Rate Reduction Due To TCJA, Amount			69
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	74
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Existing Rate Mechanism [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			20
Approved Amount Of Rate Reduction Due To TCJA	20
Interim Rate Reduction Due To TCJA, Amount			20
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	20
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			59
Approved Amount Of Rate Reduction Due To TCJA	54
Interim Rate Reduction Due To TCJA, Amount			49
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	54
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 25
Public Utilities, Requested Rate Increase (Decrease), Percentage	7.50%
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member] | Substantially All Through Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	$ 16
Interim Rate Reduction Due To TCJA, Amount			17
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	$ 16
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage	10.42%
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 112
Public Utilities, Requested Rate Increase (Decrease), Percentage	6.90%
Regulatory Matters - Kentucky Activities - CPCN and ECR Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service					155
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			108
Approved Amount Of Rate Reduction Due To TCJA	$ 101
Interim Rate Reduction Due To TCJA, Amount			91
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	101
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Existing Rate Mechanism [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			21
Approved Amount Of Rate Reduction Due To TCJA	21
Interim Rate Reduction Due To TCJA, Amount			21
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	21
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			87
Approved Amount Of Rate Reduction Due To TCJA	80
Interim Rate Reduction Due To TCJA, Amount			70
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	$ 80
LG And E And KU Energy LLC [Member] | Louisville Gas And Electric Company And Kentucky Utilities [Member]
Regulatory Matters - Federal Matters - FERC Transmission Rate Filing [Abstract]
Transmission Expenses Mitigated For Certain Customers							22
Louisville Gas And Electric Co [Member]
Regulatory Matters - Kentucky Activities - Gas Franchise (Numeric) [Abstract]
Franchise Agreement Term						5 years
Days of Notice to Modify Franchise Fee						60 days
Franchise Fee Cap						3.00%
Franchise Fee If Recovered From Customers						0.00%
Regulatory Matters - Federal Matters - FERC Transmission Rate Filing [Abstract]
Transmission Expenses Mitigated For Certain Customers							22
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage	10.42%
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 35
Public Utilities, Requested Rate Increase (Decrease), Percentage	3.00%
Regulatory Matters - Kentucky Activities - CPCN and ECR Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service					166
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Additional Amount Of Rate Reduction Due To TCJA			10
Suspended Amount Of Rate Reduction Due To TCJA			79
Approved Amount Of Rate Reduction Due To TCJA	$ 74
Approved Additional Amount Of Rate Reduction Due To TCJA	6
Interim Rate Reduction Due To TCJA, Amount			69
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	74
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Existing Rate Mechanism [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			20
Approved Amount Of Rate Reduction Due To TCJA	20
Interim Rate Reduction Due To TCJA, Amount			20
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	20
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA			59
Approved Amount Of Rate Reduction Due To TCJA	54
Interim Rate Reduction Due To TCJA, Amount			49
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	54
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 25
Public Utilities, Requested Rate Increase (Decrease), Percentage	7.50%
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member] | Substantially All Through Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	$ 16
Interim Rate Reduction Due To TCJA, Amount			17
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	$ 16
Kentucky Utilities Co [Member]
Regulatory Matters - Federal Matters - FERC Transmission Rate Filing [Abstract]
Transmission Expenses Mitigated For Certain Customers							$ 22
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage	10.42%
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 112
Public Utilities, Requested Rate Increase (Decrease), Percentage	6.90%
Regulatory Matters - Kentucky Activities - CPCN and ECR Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service					$ 155
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Additional Amount Of Rate Reduction Due To TCJA			17
Suspended Amount Of Rate Reduction Due To TCJA				$ 108
Approved Amount Of Rate Reduction Due To TCJA	$ 101
Approved Additional Amount Of Rate Reduction Due To TCJA	7
Interim Rate Reduction Due To TCJA, Amount			91
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	101
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Existing Rate Mechanism [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA				21
Approved Amount Of Rate Reduction Due To TCJA	21
Interim Rate Reduction Due To TCJA, Amount			21
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	21
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member] | Bill Credit [Member] | Tax Cuts And Jobs Act [Member]
Regulatory Matters - Kentucky Activities - TCJA [Abstract]
Suspended Amount Of Rate Reduction Due To TCJA				$ 87
Approved Amount Of Rate Reduction Due To TCJA	80
Interim Rate Reduction Due To TCJA, Amount			$ 70
Regulatory Matters - Pennsylvania Activities - TCJA (Numeric) [Abstract]
Approved Amount Of Rate Reduction Due To TCJA	$ 80