Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate	$ 115		$ 165	$ 373	$ 480
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	9		14	34	37
Valuation allowance adjustments	5		4	17	9
Impact of lower U.K. income tax rates relative to U.S. income tax rates	(7)		(45)	(20)	(133)
U.S. income tax on foreign earnings - net of foreign tax credit	1		(8)	2	(24)
Federal and state tax reserve adjustments	0		0	3	0
Impact of the U.K. Finance Acts	(4)		(3)	(7)	(12)
Depreciation and other items not normalized	(1)		(2)	(4)	(7)
Amortization of excess deferred income taxes	(11)		0	(30)	0
Deferred tax impact of state tax reform	0		0	9	0
Interest benefit on U.K. financing entities	(4)		(4)	(13)	(12)
Stock-based compensation	0		0	1	(7)
Other	0		(5)	(3)	(10)
Total increase (decrease)	(12)		(49)	(11)	(159)
Total income taxes	103		116	362	321
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities				(39)	3
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	34		74	97	181
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	6		8	17	19
Amortization of investment tax credit	(1)		(1)	(3)	(2)
Deferred tax impact of U.S. tax reform	(2)		0	(2)	0
Amortization of excess deferred income taxes	(3)		0	(14)	0
Deferred tax impact of state tax reform	0		0	9	0
Other	(2)		(2)	(2)	(3)
Total increase (decrease)	(2)		5	5	14
Total income taxes	32		79	102	195
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities				(62)	3
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	30		56	93	144
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	12		9	35	26
Depreciation and other items not normalized	(1)		(1)	(4)	(5)
Amortization of excess deferred income taxes	(5)		0	(13)	0
Stock-based compensation	0		0	0	(5)
Other	(1)		0	0	(1)
Total increase (decrease)	5		8	18	15
Total income taxes	35		64	111	159
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities				25	0
Louisville Gas And Electric Co [Member]
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate	18		36	50	91
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	3		4	9	10
Amortization of excess deferred income taxes	(1)		0	(6)	0
Other	(2)		(1)	(2)	(2)
Total increase (decrease)	0		3	1	8
Total income taxes	18		39	51	99
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities				(24)	2
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	21		43	60	111
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit	3		5	10	11
Amortization of excess deferred income taxes	(2)		0	(8)	0
Other	(1)		(1)	(3)	(2)
Total increase (decrease)	0		4	(1)	9
Total income taxes	$ 21		$ 47	59	120
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities				$ (38)	$ 1
Kentucky Utilities Co [Member] | Kentucky tax reform [Member]
Income Tax Other Numeric [Abstract]
Increase (Decrease) in Regulatory Assets and Liabilities		$ 19