Leases - Lessee (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Lease Cost [Abstract]
Operating lease cost	$ 8
Short-term lease cost	1
Total lease cost	9
Operating cash flows from operating leases	8
Right-of-use asset obtained in exchange for new operating lease liabilities	$ 4
Weighted-average remaining lease term (in years)	9 years
Operating Lease Liabilities, Payments Due [Abstract]
2019	$ 23
2020	20
2021	14
2022	10
2023	7
2024	7
Thereafter	23
Total	$ 104
2019			$ 26
2020			21
2021			15
2022			13
2023			8
Thereafter			33
Total			116
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.74%
Current lease liabilities	$ 21	$ 23
Non-current lease liabilities	64	67
Right-of-use assets	$ 76	81
LKE [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Lessee, Operating Lease, Renewal Term	1 year
LKE [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2025
Lessee, Operating Lease, Renewal Term	10 years
LGE [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Lessee, Operating Lease, Renewal Term	1 year
LGE [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2025
Lessee, Operating Lease, Renewal Term	10 years
KU [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Lessee, Operating Lease, Renewal Term	1 year
KU [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2025
Lessee, Operating Lease, Renewal Term	10 years
WPD [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
WPD [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2028
Assets and Liabilities, Lessee [Abstract]
Lessee, Operating Lease, Land Expiration Date	Dec. 31, 2116
Safari Energy [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Safari Energy [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2028
Assets and Liabilities, Lessee [Abstract]
Lessee, Operating Lease, Land Expiration Date	Dec. 31, 2116
LG And E And KU Energy LLC [Member]
Lease Cost [Abstract]
Operating lease cost	$ 7
Short-term lease cost	0
Total lease cost	7
Operating cash flows from operating leases	7
Right-of-use asset obtained in exchange for new operating lease liabilities	$ 4
Weighted-average remaining lease term (in years)	5 years
Operating Lease Liabilities, Payments Due [Abstract]
2019	$ 19
2020	15
2021	11
2022	7
2023	6
2024	5
Thereafter	5
Total	$ 68
2019			20
2020			15
2021			11
2022			7
2023			6
Thereafter			11
Total			70
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.93%
Current lease liabilities	$ 16	18
Non-current lease liabilities	43	46
Right-of-use assets	$ 51	56
LG And E And KU Energy LLC [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Lessee, Operating Lease, Renewal Term	1 year
LG And E And KU Energy LLC [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2025
Lessee, Operating Lease, Renewal Term	10 years
LG And E And KU Energy LLC [Member] | LGE [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Lessee, Operating Lease, Renewal Term	1 year
LG And E And KU Energy LLC [Member] | LGE [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2025
Lessee, Operating Lease, Renewal Term	10 years
LG And E And KU Energy LLC [Member] | KU [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Lessee, Operating Lease, Renewal Term	1 year
LG And E And KU Energy LLC [Member] | KU [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2025
Lessee, Operating Lease, Renewal Term	10 years
Louisville Gas And Electric Co [Member]
Lease Cost [Abstract]
Operating lease cost	$ 4
Short-term lease cost	0
Total lease cost	4
Operating cash flows from operating leases	4
Right-of-use asset obtained in exchange for new operating lease liabilities	$ 1
Weighted-average remaining lease term (in years)	5 years
Operating Lease Liabilities, Payments Due [Abstract]
2019	$ 8
2020	6
2021	4
2022	3
2023	3
2024	2
Thereafter	2
Total	$ 28
2019			10
2020			6
2021			4
2022			3
2023			3
Thereafter			4
Total			30
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.80%
Current lease liabilities	$ 7	9
Non-current lease liabilities	18	18
Right-of-use assets	$ 20	23
Louisville Gas And Electric Co [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Lessee, Operating Lease, Renewal Term	1 year
Louisville Gas And Electric Co [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2025
Lessee, Operating Lease, Renewal Term	10 years
Kentucky Utilities Co [Member]
Lease Cost [Abstract]
Operating lease cost	$ 3
Short-term lease cost	0
Total lease cost	3
Operating cash flows from operating leases	3
Right-of-use asset obtained in exchange for new operating lease liabilities	$ 3
Weighted-average remaining lease term (in years)	4 years
Operating Lease Liabilities, Payments Due [Abstract]
2019	$ 11
2020	8
2021	6
2022	4
2023	3
2024	3
Thereafter	3
Total	$ 38
2019			10
2020			9
2021			7
2022			4
2023			3
Thereafter			6
Total			$ 39
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	4.01%
Current lease liabilities	$ 9	9
Non-current lease liabilities	24	26
Right-of-use assets	$ 29	$ 31
Kentucky Utilities Co [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2019
Lessee, Operating Lease, Renewal Term	1 year
Kentucky Utilities Co [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Expiration Date	Dec. 31, 2025
Lessee, Operating Lease, Renewal Term	10 years