Financing Activities - Long-term Debt (Details) £ in Millions, $ in Millions	1 Months Ended					3 Months Ended
	Jul. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	May 31, 2018 USD ($)	May 31, 2018 GBP (£)	Mar. 31, 2018 GBP (£)	Mar. 31, 2018 USD ($)	Mar. 31, 2018 GBP (£)	Jun. 30, 2018 GBP (£)	May 31, 2018 GBP (£)
WPD South Wales PLC [Member] | Index Linked Senior Unsecured Notes [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount | £					£ 30		£ 30
Stated interest rate					0.01%		0.01%
Proceeds from debt, net of issuance costs | £							£ 31
Maturity date						Dec. 31, 2036	Dec. 31, 2036
Proceeds from debt, including premium net of debt issuance costs						$ 44
WPD West Midlands [Member] | Index Linked Senior Unsecured Notes [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount | £									£ 30
Stated interest rate			0.01%						0.01%
Proceeds from debt, net of issuance costs | £				£ 31
Maturity date			Dec. 31, 2028	Dec. 31, 2028
Proceeds from debt, including premium net of debt issuance costs			$ 41
PPL Capital Funding [Member] | Senior Notes [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount | £								£ 250
Stated interest rate		1.90%						1.90%
PPL Electric [Member] | First Mortgage [Member] | Mortgage Indenture 2001 [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount | £								£ 400
Stated interest rate		4.15%						4.15%
Proceeds from debt, net of issuance costs		$ 394
Maturity date		Jun. 15, 2048
LGE [Member] | Senior Debt Obligations [Member] | Pollution Control Revenue Bonds, 2001 Series A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount		$ 28
Stated interest rate		2.30%						2.30%
Maturity date					Dec. 31, 2026
Repurchase date of debt instruments					Sep. 01, 2021
LGE [Member] | Senior Debt Obligations [Member] | Pollution Control Revenue Bonds, 2001 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount			$ 35
Stated interest rate			2.55%						2.55%
Maturity date			Dec. 31, 2027	Dec. 31, 2027
Repurchase date of debt instruments			May 03, 2021	May 03, 2021
LGE [Member] | Senior Debt Obligations [Member] | Jefferson County Pollution Control Revenue Bonds, 2001 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount			$ 35
Stated interest rate			2.55%						2.55%
Maturity date			Dec. 31, 2027	Dec. 31, 2027
Repurchase date of debt instruments			May 03, 2021	May 03, 2021
KU [Member] | Senior Debt Obligations [Member] | Trimble County Environmental Facilities Revenue Bonds 2007 Series A [Member] | Subsequent Event [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount	$ 9
Maturity date	Mar. 01, 2037
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Debt Obligations [Member] | Pollution Control Revenue Bonds, 2001 Series A [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount		$ 28
Stated interest rate		2.30%						2.30%
Maturity date					Dec. 31, 2026
Repurchase date of debt instruments					Sep. 01, 2021
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Debt Obligations [Member] | Pollution Control Revenue Bonds, 2001 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount			$ 35
Stated interest rate			2.55%						2.55%
Maturity date			Dec. 31, 2027	Dec. 31, 2027
Repurchase date of debt instruments			May 03, 2021	May 03, 2021
LG And E And KU Energy LLC [Member] | LGE [Member] | Senior Debt Obligations [Member] | Jefferson County Pollution Control Revenue Bonds, 2001 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount			$ 35
Stated interest rate			2.55%						2.55%
Maturity date			Dec. 31, 2027	Dec. 31, 2027
Repurchase date of debt instruments			May 03, 2021	May 03, 2021
LG And E And KU Energy LLC [Member] | KU [Member] | Senior Debt Obligations [Member] | Trimble County Environmental Facilities Revenue Bonds 2007 Series A [Member] | Subsequent Event [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount	$ 9
Maturity date	Mar. 01, 2037
LG And E And KU Energy LLC [Member] | Affiliated Entity [Member] | Note Payable [Member]
Long-term Debt (Numeric) [Abstract]
Stated interest rate			4.00%						4.00%
Maturity date			May 31, 2028	May 31, 2028
Notes Payable, Noncurrent			$ 250
Louisville Gas And Electric Co [Member] | Senior Debt Obligations [Member] | Pollution Control Revenue Bonds, 2001 Series A [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount		$ 28
Stated interest rate		2.30%						2.30%
Maturity date					Dec. 31, 2026
Repurchase date of debt instruments					Sep. 01, 2021
Louisville Gas And Electric Co [Member] | Senior Debt Obligations [Member] | Pollution Control Revenue Bonds, 2001 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount			$ 35
Stated interest rate			2.55%						2.55%
Maturity date			Dec. 31, 2027	Dec. 31, 2027
Repurchase date of debt instruments			May 03, 2021	May 03, 2021
Louisville Gas And Electric Co [Member] | Senior Debt Obligations [Member] | Jefferson County Pollution Control Revenue Bonds, 2001 Series B [Member] | Remarketed [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount			$ 35
Stated interest rate			2.55%						2.55%
Maturity date			Dec. 31, 2027	Dec. 31, 2027
Repurchase date of debt instruments			May 03, 2021	May 03, 2021
Kentucky Utilities Co [Member] | Senior Debt Obligations [Member] | Trimble County Environmental Facilities Revenue Bonds 2007 Series A [Member] | Subsequent Event [Member]
Long-term Debt (Numeric) [Abstract]
Principal amount	$ 9
Maturity date	Mar. 01, 2037