Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate	$ 138	$ 129	$ 257	$ 315
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	10	10	25	23
Valuation allowance adjustments	5	0	12	5
Impact of lower U.K. income tax rates relative to U.S. income tax rates	(6)	(40)	(13)	(88)
U.S. income tax on foreign earnings - net of foreign tax credit	0	(7)	1	(16)
Federal and state tax reserve adjustments	3	0	3	0
Impact of the U.K. Finance Acts	(2)	(6)	(3)	(9)
Depreciation and other items not normalized	(2)	(2)	(4)	(5)
Amortization of excess deferred income taxes	(9)	0	(19)	0
Deferred tax impact of state tax reform	9	0	9	0
Interest benefit on U.K. financing entities	(4)	(4)	(9)	(8)
Stock-based compensation	0	(4)	1	(7)
Other	0	0	(1)	(5)
Total increase (decrease)	4	(53)	2	(110)
Total income taxes	142	76	259	205
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities			(42)	19
LKE [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Deferred Income Tax Expense (Benefit)	9
LGE [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities	16
KU [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities	19
LG And E And KU Energy LLC [Member]
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate	25	49	63	107
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	3	5	11	11
Amortization of excess deferred income taxes	(6)	0	(11)	0
Deferred tax impact of state tax reform	9	0	9	0
Other	0	(1)	(2)	(2)
Total increase (decrease)	6	4	7	9
Total income taxes	31	53	70	116
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities			(69)	7
LG And E And KU Energy LLC [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Deferred Income Tax Expense (Benefit)	9
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities	16
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities	19
PPL Electric Utilities Corp [Member]
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate	22	44	63	88
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	8	9	24	17
Depreciation and other items not normalized	(1)	(2)	(3)	(4)
Amortization of excess deferred income taxes	(3)	0	(8)	0
Stock-based compensation	0	(3)	0	(5)
Other	1	(1)	0	(1)
Total increase (decrease)	5	3	13	7
Total income taxes	27	47	76	95
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities			27	12
Louisville Gas And Electric Co [Member]
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate	13	24	33	55
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	2	3	6	6
Amortization of excess deferred income taxes	(3)	0	(5)	0
Other	0	0	(1)	(1)
Total increase (decrease)	(1)	3	0	5
Total income taxes	12	27	33	60
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities			(32)	3
Louisville Gas And Electric Co [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities	16
Kentucky Utilities Co [Member]
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate	16	32	39	67
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	2	3	7	7
Amortization of excess deferred income taxes	(3)	0	(6)	0
Other	(1)	(1)	(2)	(1)
Total increase (decrease)	(2)	2	(1)	6
Total income taxes	14	$ 34	38	73
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities			$ (37)	$ 4
Kentucky Utilities Co [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities	$ 19