Utility Rate Regulation - Regulatory Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Regulatory Liabilities [Line Items]
Current regulatory liabilities	$ 136	$ 95
Noncurrent regulatory liabilities	2,739	2,704
Generation Supply Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	35	34
Transmission Service Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	2	9
Environmental Cost Recovery [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	22	1
Universal Service Rider [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	23	26
Transmission Formula Rate [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	8	9
Fuel adjustment clause [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	7	3
TCJA customer refund [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	26	0
Noncurrent regulatory liabilities	41	0
Storm Damage Expense Rider [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4	8
Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	678	677
Power Purchase Agreement OVEC [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	62	68
Net deferred taxes [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	1,846	1,853
Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	33	27
Terminated interest rate swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	72	74
Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	9	5
Noncurrent regulatory liabilities	7	5
PPL Electric Utilities Corp [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	72	86
Noncurrent regulatory liabilities	686	668
PPL Electric Utilities Corp [Member] | Generation Supply Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	35	34
PPL Electric Utilities Corp [Member] | Transmission Service Charge [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	2	9
PPL Electric Utilities Corp [Member] | Environmental Cost Recovery [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	0	0
PPL Electric Utilities Corp [Member] | Universal Service Rider [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	23	26
PPL Electric Utilities Corp [Member] | Transmission Formula Rate [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	8	9
PPL Electric Utilities Corp [Member] | Fuel adjustment clause [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	0	0
PPL Electric Utilities Corp [Member] | TCJA customer refund [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	0	0
Noncurrent regulatory liabilities	41	0
PPL Electric Utilities Corp [Member] | Storm Damage Expense Rider [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	4	8
PPL Electric Utilities Corp [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	0	0
PPL Electric Utilities Corp [Member] | Power Purchase Agreement OVEC [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	0	0
PPL Electric Utilities Corp [Member] | Net deferred taxes [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	642	668
PPL Electric Utilities Corp [Member] | Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	0	0
PPL Electric Utilities Corp [Member] | Terminated interest rate swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	0	0
PPL Electric Utilities Corp [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	0	0
Noncurrent regulatory liabilities	3	0
LG And E And KU Energy LLC [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	64	9
Noncurrent regulatory liabilities	2,053	2,036
LG And E And KU Energy LLC [Member] | Environmental Cost Recovery [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	22	1
LG And E And KU Energy LLC [Member] | Fuel adjustment clause [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	7	3
LG And E And KU Energy LLC [Member] | Gas Line Tracker [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	2	3
LG And E And KU Energy LLC [Member] | TCJA customer refund [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	26	0
LG And E And KU Energy LLC [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	678	677
LG And E And KU Energy LLC [Member] | Power Purchase Agreement OVEC [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	62	68
LG And E And KU Energy LLC [Member] | Net deferred taxes [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	1,204	1,185
LG And E And KU Energy LLC [Member] | Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	33	27
LG And E And KU Energy LLC [Member] | Terminated interest rate swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	72	74
LG And E And KU Energy LLC [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	7	2
Noncurrent regulatory liabilities	4	5
Louisville Gas And Electric Co [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	26	3
Noncurrent regulatory liabilities	920	919
Louisville Gas And Electric Co [Member] | Environmental Cost Recovery [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	11	0
Louisville Gas And Electric Co [Member] | Fuel adjustment clause [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	0	0
Louisville Gas And Electric Co [Member] | Gas Line Tracker [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	2	3
Louisville Gas And Electric Co [Member] | TCJA customer refund [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	12	0
Louisville Gas And Electric Co [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	280	282
Louisville Gas And Electric Co [Member] | Power Purchase Agreement OVEC [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	43	47
Louisville Gas And Electric Co [Member] | Net deferred taxes [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	560	552
Louisville Gas And Electric Co [Member] | Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	0	0
Louisville Gas And Electric Co [Member] | Terminated interest rate swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	36	37
Louisville Gas And Electric Co [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1	0
Noncurrent regulatory liabilities	1	1
Kentucky Utilities Co [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	38	6
Noncurrent regulatory liabilities	1,133	1,117
Kentucky Utilities Co [Member] | Environmental Cost Recovery [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	11	1
Kentucky Utilities Co [Member] | Fuel adjustment clause [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	7	3
Kentucky Utilities Co [Member] | Gas Line Tracker [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	0	0
Kentucky Utilities Co [Member] | TCJA customer refund [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	14	0
Kentucky Utilities Co [Member] | Accumulated Cost Of Removal Of Utility Plant [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	398	395
Kentucky Utilities Co [Member] | Power Purchase Agreement OVEC [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	19	21
Kentucky Utilities Co [Member] | Net deferred taxes [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	644	633
Kentucky Utilities Co [Member] | Defined Benefit Plans [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	33	27
Kentucky Utilities Co [Member] | Terminated interest rate swaps [Member]
Regulatory Liabilities [Line Items]
Noncurrent regulatory liabilities	36	37
Kentucky Utilities Co [Member] | Other Regulatory Liabilities [Member]
Regulatory Liabilities [Line Items]
Current regulatory liabilities	6	2
Noncurrent regulatory liabilities	$ 3	$ 4