Utility Rate Regulation - Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Regulatory Assets [Line Items]
Current regulatory assets	$ 29	$ 34
Noncurrent regulatory assets	1,525	1,504
Environmental Cost Recovery [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	5
Generation Formula Rate [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	6
Smart Meter Rider [Member]
Regulatory Assets [Line Items]
Current regulatory assets	16	15
Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	7	3
Gas Supply Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	3	4
Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	847	880
Taxes Recoverable Through Future Rates [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	3	3
Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	45	33
Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	47	54
Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	18	26
Terminated Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	88	92
Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	190	173
Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	267	234
Act 129 Compliance Rider [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	12	0
Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	3	1
Noncurrent regulatory assets	8	9
PPL Electric Utilities Corp [Member]
Regulatory Assets [Line Items]
Current regulatory assets	18	16
Noncurrent regulatory assets	738	709
PPL Electric Utilities Corp [Member] | Environmental Cost Recovery [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Generation Formula Rate [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Smart Meter Rider [Member]
Regulatory Assets [Line Items]
Current regulatory assets	16	15
PPL Electric Utilities Corp [Member] | Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Gas Supply Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	486	504
PPL Electric Utilities Corp [Member] | Taxes Recoverable Through Future Rates [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	3	3
PPL Electric Utilities Corp [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	22	0
PPL Electric Utilities Corp [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	23	29
PPL Electric Utilities Corp [Member] | Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Terminated Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	190	173
PPL Electric Utilities Corp [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Act 129 Compliance Rider [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	12	0
PPL Electric Utilities Corp [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	2	1
Noncurrent regulatory assets	2	0
LG And E And KU Energy LLC [Member]
Regulatory Assets [Line Items]
Current regulatory assets	11	18
Noncurrent regulatory assets	787	795
LG And E And KU Energy LLC [Member] | Generation Formula Rate [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	6
LG And E And KU Energy LLC [Member] | Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	7	3
LG And E And KU Energy LLC [Member] | Gas Supply Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	3	4
LG And E And KU Energy LLC [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	361	376
LG And E And KU Energy LLC [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	23	33
LG And E And KU Energy LLC [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	24	25
LG And E And KU Energy LLC [Member] | Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	18	26
LG And E And KU Energy LLC [Member] | Terminated Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	88	92
LG And E And KU Energy LLC [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	267	234
LG And E And KU Energy LLC [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	1	5
Noncurrent regulatory assets	6	9
Louisville Gas And Electric Co [Member]
Regulatory Assets [Line Items]
Current regulatory assets	11	12
Noncurrent regulatory assets	400	411
Louisville Gas And Electric Co [Member] | Generation Formula Rate [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
Louisville Gas And Electric Co [Member] | Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	7	3
Louisville Gas And Electric Co [Member] | Gas Supply Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	3	4
Louisville Gas And Electric Co [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	227	234
Louisville Gas And Electric Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	12	18
Louisville Gas And Electric Co [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	15	16
Louisville Gas And Electric Co [Member] | Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	18	26
Louisville Gas And Electric Co [Member] | Terminated Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	52	54
Louisville Gas And Electric Co [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	74	61
Louisville Gas And Electric Co [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	1	5
Noncurrent regulatory assets	2	2
Kentucky Utilities Co [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	6
Noncurrent regulatory assets	387	384
Kentucky Utilities Co [Member] | Generation Formula Rate [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	6
Kentucky Utilities Co [Member] | Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
Kentucky Utilities Co [Member] | Gas Supply Clause [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
Kentucky Utilities Co [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	134	142
Kentucky Utilities Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	11	15
Kentucky Utilities Co [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	9	9
Kentucky Utilities Co [Member] | Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	0	0
Kentucky Utilities Co [Member] | Terminated Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	36	38
Kentucky Utilities Co [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	193	173
Kentucky Utilities Co [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
Noncurrent regulatory assets	$ 4	$ 7