Utility Rate Regulation - Regulatory Assets (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Regulatory Assets [Line Items]
Current regulatory assets	$ 28	$ 34
Noncurrent regulatory assets	1,519	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	2	6
Smart Meter Rider [Member]
Regulatory Assets [Line Items]
Current regulatory assets	15	15
Act 129 Compliance Rider [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	7	0
Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	866	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	47	33
Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	51	54
Interest Rate Swaps [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	22	26
Terminated Interest Rate Swap [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	91	92
Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	176	173
Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	247	234
Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	6	3
Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	5	5
Noncurrent regulatory assets	9	9
PPL Electric Utilities Corp [Member]
Regulatory Assets [Line Items]
Current regulatory assets	16	16
Noncurrent regulatory assets	726	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	15	15
PPL Electric Utilities Corp [Member] | Act 129 Compliance Rider [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	7	0
PPL Electric Utilities Corp [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	496	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	17	0
PPL Electric Utilities Corp [Member] | Unamortized Loss On Debt [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	27	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 Swap [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	176	173
PPL Electric Utilities Corp [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
PPL Electric Utilities Corp [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	1	1
Noncurrent regulatory assets	0	0
LG And E And KU Energy LLC [Member]
Regulatory Assets [Line Items]
Current regulatory assets	12	18
Noncurrent regulatory assets	793	795
LG And E And KU Energy LLC [Member] | Environmental Cost Recovery [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	5
LG And E And KU Energy LLC [Member] | Generation Formula Rate [Member]
Regulatory Assets [Line Items]
Current regulatory assets	2	6
LG And E And KU Energy LLC [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	370	376
LG And E And KU Energy LLC [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	30	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	22	26
LG And E And KU Energy LLC [Member] | Terminated Interest Rate Swap [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	91	92
LG And E And KU Energy LLC [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	247	234
LG And E And KU Energy LLC [Member] | Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	6	3
LG And E And KU Energy LLC [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	4	4
Noncurrent regulatory assets	9	9
Louisville Gas And Electric Co [Member]
Regulatory Assets [Line Items]
Current regulatory assets	10	12
Noncurrent regulatory assets	406	411
Louisville Gas And Electric Co [Member] | Environmental Cost Recovery [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	5
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] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	230	234
Louisville Gas And Electric Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	16	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	22	26
Louisville Gas And Electric Co [Member] | Terminated Interest Rate Swap [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	53	54
Louisville Gas And Electric Co [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	67	61
Louisville Gas And Electric Co [Member] | Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	6	3
Louisville Gas And Electric Co [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	4	4
Noncurrent regulatory assets	3	2
Kentucky Utilities Co [Member]
Regulatory Assets [Line Items]
Current regulatory assets	2	6
Noncurrent regulatory assets	387	384
Kentucky Utilities Co [Member] | Environmental Cost Recovery [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
Kentucky Utilities Co [Member] | Generation Formula Rate [Member]
Regulatory Assets [Line Items]
Current regulatory assets	2	6
Kentucky Utilities Co [Member] | Defined Benefit Plans [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	140	142
Kentucky Utilities Co [Member] | Storm Costs [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	14	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 Swap [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	38	38
Kentucky Utilities Co [Member] | Asset Retirement Obligations [Member]
Regulatory Assets [Line Items]
Noncurrent regulatory assets	180	173
Kentucky Utilities Co [Member] | Plant outage costs [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
Kentucky Utilities Co [Member] | Other Regulatory Assets [Member]
Regulatory Assets [Line Items]
Current regulatory assets	0	0
Noncurrent regulatory assets	$ 6	$ 7