Utility Rate Regulation - Regulatory Matters (Details) - Kentucky Public Service Commission [Member] - USD ($) $ in Millions	Apr. 30, 2019	Mar. 01, 2019	Sep. 28, 2018
LKE [Member] | Electric And Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Estimated Total Revenue Increase	$ 187
LGE [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage			10.42%
Public Utilities Proposed Return On Equity Percentage		9.725%
LGE [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 35
Public Utilities Proposed Rate Increase Decrease Amount		$ 4
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		40
LGE [Member] | Electric Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	2
LGE [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 25
Public Utilities Proposed Rate Increase Decrease Amount		20
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		$ 12
LGE [Member] | Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	19
LGE [Member] | Electric And Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Estimated Total Revenue Increase	73
KU [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage			10.42%
Public Utilities Proposed Return On Equity Percentage		9.725%
KU [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 112
Public Utilities Proposed Rate Increase Decrease Amount		$ 58
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		$ 58
KU [Member] | Electric Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	56
KU [Member] | Electric And Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Estimated Total Revenue Increase	114
LG And E And KU Energy LLC [Member] | Electric And Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Estimated Total Revenue Increase	187
LG And E And KU Energy LLC [Member] | LGE [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage			10.42%
Public Utilities Proposed Return On Equity Percentage		9.725%
LG And E And KU Energy LLC [Member] | LGE [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 35
Public Utilities Proposed Rate Increase Decrease Amount		$ 4
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		40
LG And E And KU Energy LLC [Member] | LGE [Member] | Electric Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	2
LG And E And KU Energy LLC [Member] | LGE [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 25
Public Utilities Proposed Rate Increase Decrease Amount		20
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		$ 12
LG And E And KU Energy LLC [Member] | LGE [Member] | Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	19
LG And E And KU Energy LLC [Member] | LGE [Member] | Electric And Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Estimated Total Revenue Increase	73
LG And E And KU Energy LLC [Member] | KU [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage			10.42%
Public Utilities Proposed Return On Equity Percentage		9.725%
LG And E And KU Energy LLC [Member] | KU [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 112
Public Utilities Proposed Rate Increase Decrease Amount		$ 58
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		$ 58
LG And E And KU Energy LLC [Member] | KU [Member] | Electric Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	56
LG And E And KU Energy LLC [Member] | KU [Member] | Electric And Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Estimated Total Revenue Increase	114
Louisville Gas And Electric Co [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage			10.42%
Public Utilities Proposed Return On Equity Percentage		9.725%
Louisville Gas And Electric Co [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 35
Public Utilities Proposed Rate Increase Decrease Amount		$ 4
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		40
Louisville Gas And Electric Co [Member] | Electric Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	2
Louisville Gas And Electric Co [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 25
Public Utilities Proposed Rate Increase Decrease Amount		20
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		$ 12
Louisville Gas And Electric Co [Member] | Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	19
Louisville Gas And Electric Co [Member] | Electric And Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Estimated Total Revenue Increase	73
Kentucky Utilities Co [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Return on Equity, Percentage			10.42%
Public Utilities Proposed Return On Equity Percentage		9.725%
Kentucky Utilities Co [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 112
Public Utilities Proposed Rate Increase Decrease Amount		$ 58
Public Utilities, Revenue Increase due to Elimination of TCJA Bill Credit		$ 58
Kentucky Utilities Co [Member] | Electric Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Approved Rate Increase (Decrease), Amount	56
Kentucky Utilities Co [Member] | Electric And Gas Rates [Member] | Subsequent Event [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Estimated Total Revenue Increase	$ 114