Utility Rate Regulation - Regulatory Matters (Details) - USD ($) $ in Millions				1 Months Ended	3 Months Ended
	Mar. 20, 2018	Jan. 29, 2018	Jan. 10, 2018	Aug. 31, 2016	Mar. 31, 2018	Mar. 31, 2017
LKE [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase Decrease Amended Amount	$ 27
LGE [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (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] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Gas Service			62
Advanced Metering Systems Deployment Incremental O&M Cost, Gas Service			3
LGE [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		$ 69
Approved Revenue Reduction Refunded Through Existing Mechanisms	20
Approved Revenue Reduction Refunded Through New Bill Credit	59
Public Utilities, Approved Rate Increase (Decrease), Amount	79
Proposed Revenue Reduction Refunded Through Existing Mechanisms		20
Proposed Revenue Reduction Refunded Through New Bill Credit		49
LGE [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		17
KU [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service			155
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service			17
KU [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		91
Approved Revenue Reduction Refunded Through Existing Mechanisms	21
Approved Revenue Reduction Refunded Through New Bill Credit	87
Public Utilities, Approved Rate Increase (Decrease), Amount	108
Proposed Revenue Reduction Refunded Through Existing Mechanisms		21
Proposed Revenue Reduction Refunded Through New Bill Credit		70
LG And E And KU Energy LLC [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase Decrease Amended Amount	27
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] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (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] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (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] | LGE [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		69
Approved Revenue Reduction Refunded Through Existing Mechanisms	20
Approved Revenue Reduction Refunded Through New Bill Credit	59
Public Utilities, Approved Rate Increase (Decrease), Amount	79
Proposed Revenue Reduction Refunded Through Existing Mechanisms		20
Proposed Revenue Reduction Refunded Through New Bill Credit		49
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		17
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]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service			155
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service			17
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		91
Approved Revenue Reduction Refunded Through Existing Mechanisms	21
Approved Revenue Reduction Refunded Through New Bill Credit	87
Public Utilities, Approved Rate Increase (Decrease), Amount	108
Proposed Revenue Reduction Refunded Through Existing Mechanisms		21
Proposed Revenue Reduction Refunded Through New Bill Credit		70
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] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (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] | Kentucky Public Service Commission [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Gas Service			62
Advanced Metering Systems Deployment Incremental O&M Cost, Gas Service			3
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		69
Approved Revenue Reduction Refunded Through Existing Mechanisms	20
Approved Revenue Reduction Refunded Through New Bill Credit	59
Public Utilities, Approved Rate Increase (Decrease), Amount	79
Public Utilities, Proposed Rate Increase Decrease Amended Amount	10
Proposed Revenue Reduction Refunded Through Existing Mechanisms		20
Proposed Revenue Reduction Refunded Through New Bill Credit		49
Louisville Gas And Electric Co [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Gas Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		17
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Advanced Metering Systems Deployment Estimated Capital Cost, Electric Service			155
Advanced Metering Systems Deployment Incremental O&M Cost, Electric Service			$ 17
Kentucky Utilities Co [Member] | Kentucky Public Service Commission [Member] | TCJA Savings Distributed To Customers [Member] | Electric Rates [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Public Utilities, Proposed Rate Increase (Decrease), Amount		91
Approved Revenue Reduction Refunded Through Existing Mechanisms	21
Approved Revenue Reduction Refunded Through New Bill Credit	87
Public Utilities, Approved Rate Increase (Decrease), Amount	108
Public Utilities, Proposed Rate Increase Decrease Amended Amount	$ 17
Proposed Revenue Reduction Refunded Through Existing Mechanisms		21
Proposed Revenue Reduction Refunded Through New Bill Credit		$ 70
Unaffiliated Third Party Entity [Member] | PPL Electric [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Purchases of Accounts Receivable					$ 376	$ 356
Unaffiliated Third Party Entity [Member] | PPL Electric Utilities Corp [Member]
Regulatory Matters - Kentucky Activities - Rate Case Proceedings (Numeric) [Abstract]
Purchases of Accounts Receivable					$ 376	$ 356