Utility Rate Regulation (Regulatory Matters) (Details) $ in Millions				1 Months Ended			12 Months Ended
	Jan. 29, 2018 USD ($)	Jan. 10, 2018 USD ($)	Jun. 23, 2017	Jun. 30, 2017 USD ($)	May 31, 2017 USD ($)	Aug. 31, 2016	Dec. 31, 2017 USD ($) Integer
Regulatory Matters - United Kingdom Activities - Ofgem Review of Line Loss Calculation (Numeric) [Abstract]
Number Of Distribution Network Operators | Integer							4
PPL Electric [Member] | Act 129 Compliance Rider [Member]
Regulatory Matters - Pennsylvania Activities - Act 129 (Numeric) [Abstract]
Minimum term of long term supply contract under Act 129 (in years)							4 years
Maximum term of long term supply contract under Act 129 (in years)							20 years
Maximum percentage of long-term contracts that can be included in the mix of PLR supply contracts under Act 129							25.00%
Maximum amount of costs that can be recovered under the Act 129 Phase III plan							$ 313
Period over which program costs can be recovered (in years)							5 years
LKE [Member] | Kentucky Public Service Commission [Member] | Depreciation Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Depreciation Rate Increase (Decrease)				$ 15
LGE [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans			10.00%
Return On Equity Approved Projects In 2016 Environmental Cost Recovery Proceedings			9.80%
Return On Equity For All Existing Approved Environmental Cost Recovery Plans And Projects			9.70%
Return on equity							9.70%
Amortization period for the deferred recovery of a regulatory asset							12 months
LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Percentage				5.20%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 59
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 57
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 59
LGE [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Percentage				2.10%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 8
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 7
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 8
LGE [Member] | Subsequent Event [Member] | Electric Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	$ 69
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	69
LGE [Member] | Subsequent Event [Member] | Gas Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	17
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	17
LGE [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service		$ 104
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service		11
LGE [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Gas Service		62
Advanced Metering Systems Deployment Incremental O&M Cost, Gas Service		3
KU [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans			10.00%
Return On Equity Approved Projects In 2016 Environmental Cost Recovery Proceedings			9.80%
Return On Equity For All Existing Approved Environmental Cost Recovery Plans And Projects			9.70%
Return on equity							9.70%
Amortization period for the deferred recovery of a regulatory asset							12 months
KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Percentage				3.20%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 55
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 52
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 55
KU [Member] | Subsequent Event [Member] | Electric Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	91
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	91
KU [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service		155
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service		17
PPL Electric Utilities Corp [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Amortization period for the deferred recovery of a regulatory asset							5 years
Regulatory Matters - Pennsylvania Activities - Act 129 (Numeric) [Abstract]
Minimum term of long term supply contract under Act 129 (in years)							4 years
Maximum term of long term supply contract under Act 129 (in years)							20 years
Maximum percentage of long-term contracts that can be included in the mix of PLR supply contracts under Act 129							25.00%
Maximum amount of costs that can be recovered under the Act 129 Phase III plan							$ 313
Period over which program costs can be recovered (in years)							5 years
PPL Electric Utilities Corp [Member] | Act 129 Compliance Rider [Member]
Regulatory Matters - Pennsylvania Activities - Act 129 (Numeric) [Abstract]
Maximum amount of costs that can be recovered under the Act 129 Phase III plan							$ 313
Period over which program costs can be recovered (in years)							5 years
LG And E And KU Energy LLC [Member] | Kentucky Public Service Commission [Member] | Depreciation Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Depreciation Rate Increase (Decrease)				$ 15
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] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans			10.00%
Return On Equity Approved Projects In 2016 Environmental Cost Recovery Proceedings			9.80%
Return On Equity For All Existing Approved Environmental Cost Recovery Plans And Projects			9.70%
Return on equity							9.70%
Amortization period for the deferred recovery of a regulatory asset							12 months
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, Approved Rate Increase (Decrease), Percentage				5.20%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 59
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 57
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 59
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, Approved Rate Increase (Decrease), Percentage				2.10%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 8
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 7
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 8
LG And E And KU Energy LLC [Member] | LGE [Member] | Subsequent Event [Member] | Electric Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	69
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	69
LG And E And KU Energy LLC [Member] | LGE [Member] | Subsequent Event [Member] | Gas Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	17
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	17
LG And E And KU Energy LLC [Member] | LGE [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service		104
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service		11
LG And E And KU Energy LLC [Member] | LGE [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Gas Service		62
Advanced Metering Systems Deployment Incremental O&M Cost, Gas Service		3
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans			10.00%
Return On Equity Approved Projects In 2016 Environmental Cost Recovery Proceedings			9.80%
Return On Equity For All Existing Approved Environmental Cost Recovery Plans And Projects			9.70%
Return on equity							9.70%
Amortization period for the deferred recovery of a regulatory asset							12 months
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, Approved Rate Increase (Decrease), Percentage				3.20%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 55
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 52
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 55
LG And E And KU Energy LLC [Member] | KU [Member] | Subsequent Event [Member] | Electric Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	91
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	91
LG And E And KU Energy LLC [Member] | KU [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service		155
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service		17
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%
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans			10.00%
Return On Equity Approved Projects In 2016 Environmental Cost Recovery Proceedings			9.80%
Return On Equity For All Existing Approved Environmental Cost Recovery Plans And Projects			9.70%
Return on equity							9.70%
Amortization period for the deferred recovery of a regulatory asset							12 months
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, Approved Rate Increase (Decrease), Percentage				5.20%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 59
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 57
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 59
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, Approved Rate Increase (Decrease), Percentage				2.10%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 8
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 7
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 8
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Depreciation Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Depreciation Rate Increase (Decrease)				$ 4
Louisville Gas And Electric Co [Member] | Subsequent Event [Member] | Electric Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	69
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	69
Louisville Gas And Electric Co [Member] | Subsequent Event [Member] | Gas Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	17
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	17
Louisville Gas And Electric Co [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service		104
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service		11
Louisville Gas And Electric Co [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Gas Service		62
Advanced Metering Systems Deployment Incremental O&M Cost, Gas Service		3
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Return on equity for approved projects remaining from earlier ECR plans			10.00%
Return On Equity Approved Projects In 2016 Environmental Cost Recovery Proceedings			9.80%
Return On Equity For All Existing Approved Environmental Cost Recovery Plans And Projects			9.70%
Return on equity							9.70%
Amortization period for the deferred recovery of a regulatory asset							12 months
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Percentage				3.20%
Public Utilities Proposed Return On Equity Percentage					9.75%
Public Utilities Proposed Rate Increase Decrease Amount					$ 55
Increase in annual revenue requirements associated with base rates resulting from rate case				$ 52
Return on equity				9.70%
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount					$ 55
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Depreciation Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Depreciation Rate Increase (Decrease)				$ 11
Kentucky Utilities Co [Member] | Subsequent Event [Member] | Electric Rates [Member] | TCJA Savings Distributed To Customers [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	91
Regulatory Matters - Kentucky Activities - TCJA Impact On LG&E And KU Rates [Abstract]
Public Utilities Proposed Rate Increase Decrease Amount	$ 91
Kentucky Utilities Co [Member] | Subsequent Event [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - CPCN Filings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service		155
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service		$ 17