Utility Rate Regulation - Regulatory Matters (Details) - USD ($) $ in Millions				1 Months Ended
	Jun. 29, 2017	Jun. 23, 2017	Apr. 19, 2017	Aug. 31, 2016
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), Amount	$ 15
LGE [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Return on Equity Increase (Decrease), Percentage			9.75%
Public Utilities, Approved Return on Equity, Percentage	9.70%
LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount			$ 59
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 57
Public Utilities, Approved Rate Increase (Decrease), Percentage	5.20%
LGE [Member] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount			$ 8
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 7
Public Utilities, Approved Rate Increase (Decrease), Percentage	2.10%
LGE [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Return on Equity All Existing Approved Environmental Cost Recovery Plans And Projects Increase (Decrease), Percentage		9.70%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery All Other Projects, Percentage		10.00%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery CCRs, Percentage		9.80%
KU [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Return on Equity Increase (Decrease), Percentage			9.75%
Public Utilities, Approved Return on Equity, Percentage	9.70%
KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount			$ 55
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 52
Public Utilities, Approved Rate Increase (Decrease), Percentage	3.20%
KU [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Return on Equity All Existing Approved Environmental Cost Recovery Plans And Projects Increase (Decrease), Percentage		9.70%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery All Other Projects, Percentage		10.00%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery CCRs, Percentage		9.80%
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), Amount	$ 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]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Return on Equity Increase (Decrease), Percentage			9.75%
Public Utilities, Approved Return on Equity, Percentage	9.70%
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, Proposed Rate Increase (Decrease), Amount			$ 59
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 57
Public Utilities, Approved Rate Increase (Decrease), Percentage	5.20%
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, Proposed Rate Increase (Decrease), Amount			$ 8
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 7
Public Utilities, Approved Rate Increase (Decrease), Percentage	2.10%
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]
Public Utilities, Approved Return on Equity All Existing Approved Environmental Cost Recovery Plans And Projects Increase (Decrease), Percentage		9.70%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery All Other Projects, Percentage		10.00%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery CCRs, Percentage		9.80%
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, Proposed Return on Equity Increase (Decrease), Percentage			9.75%
Public Utilities, Approved Return on Equity, Percentage	9.70%
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, Proposed Rate Increase (Decrease), Amount			$ 55
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 52
Public Utilities, Approved Rate Increase (Decrease), Percentage	3.20%
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]
Public Utilities, Approved Return on Equity All Existing Approved Environmental Cost Recovery Plans And Projects Increase (Decrease), Percentage		9.70%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery All Other Projects, Percentage		10.00%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery CCRs, Percentage		9.80%
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]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Return on Equity Increase (Decrease), Percentage			9.75%
Public Utilities, Approved Return on Equity, Percentage	9.70%
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, Proposed Rate Increase (Decrease), Amount			$ 59
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 57
Public Utilities, Approved Rate Increase (Decrease), Percentage	5.20%
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, Proposed Rate Increase (Decrease), Amount			$ 8
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 7
Public Utilities, Approved Rate Increase (Decrease), Percentage	2.10%
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), Amount	$ 4
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Return on Equity All Existing Approved Environmental Cost Recovery Plans And Projects Increase (Decrease), Percentage		9.70%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery All Other Projects, Percentage		10.00%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery CCRs, Percentage		9.80%
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Return on Equity Increase (Decrease), Percentage			9.75%
Public Utilities, Approved Return on Equity, Percentage	9.70%
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount			$ 55
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 52
Public Utilities, Approved Rate Increase (Decrease), Percentage	3.20%
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), Amount	$ 11
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Environmental Cost Recovery [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Return on Equity All Existing Approved Environmental Cost Recovery Plans And Projects Increase (Decrease), Percentage		9.70%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery All Other Projects, Percentage		10.00%
Public Utilities, Prior Approved Return on Equity Approved Environmental Cost Recovery CCRs, Percentage		9.80%