Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended
	Apr. 13, 2018	Mar. 31, 2018	Mar. 31, 2017
Income Taxes [Line Items]
Increase (Decrease) in Regulatory Assets and Liabilities		$ (64)	$ 17
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate		119	186
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit		15	13
Valuation allowance adjustments		7	5
Impact of lower U.K. income tax rates relative to U.S. income tax rates		(7)	(48)
U.S. income tax on foreign earnings - net of foreign tax credit		1	(9)
Impact of the U.K. Finance Acts		(1)	(3)
Depreciation and other items not normalized		(12)	(3)
Interest benefit on U.K. financing entities		(5)	(4)
Stock-based compensation		1	(3)
Other		(1)	(5)
Total increase (decrease)		(2)	(57)
Total income taxes		117	129
LKE [Member] | Tax Cuts And Jobs Act [Member] | Subsequent Event [Member]
Income Taxes [Line Items]
Deferred Income Tax Expense (Benefit)	$ 9
LGE [Member] | Kentucky tax reform [Member] | Subsequent Event [Member]
Income Taxes [Line Items]
Increase (Decrease) in Regulatory Assets and Liabilities	16
KU [Member] | Kentucky tax reform [Member] | Subsequent Event [Member]
Income Taxes [Line Items]
Increase (Decrease) in Regulatory Assets and Liabilities	19
PPL Electric Utilities Corp [Member]
Income Taxes [Line Items]
Increase (Decrease) in Regulatory Assets and Liabilities		(5)	11
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate		41	44
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit		15	8
Depreciation and other items not normalized		(7)	(2)
Stock-based compensation		0	(2)
Other		0	0
Total increase (decrease)		8	4
Total income taxes		49	48
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		38	58
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit		8	6
Amortization of investment tax credit		0	0
Depreciation and other items not normalized		(5)	0
Stock-based compensation		0	0
Other		(2)	(1)
Total increase (decrease)		1	5
Total income taxes		39	63
LG And E And KU Energy LLC [Member] | Kentucky tax reform [Member] | Subsequent Event [Member]
Income Taxes [Line Items]
Deferred Income Tax Expense (Benefit)	9
LG And E And KU Energy LLC [Member] | LGE [Member] | Kentucky tax reform [Member] | Subsequent Event [Member]
Income Taxes [Line Items]
Increase (Decrease) in Regulatory Assets and Liabilities	16
LG And E And KU Energy LLC [Member] | KU [Member] | Kentucky tax reform [Member] | Subsequent Event [Member]
Income Taxes [Line Items]
Increase (Decrease) in Regulatory Assets and Liabilities	19
Louisville Gas And Electric Co [Member]
Reconciliation of Income Tax Expense [Abstract]
Federal income tax on Income Before Income Taxes at statutory tax rate		20	30
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit		4	3
Depreciation and other items not normalized		(2)	0
Other		(1)	0
Total increase (decrease)		1	3
Total income taxes		21	33
Louisville Gas And Electric Co [Member] | Kentucky tax reform [Member] | Subsequent Event [Member]
Income Taxes [Line Items]
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		23	36
Increase (decrease) due to: [Abstract]
State income taxes, net of federal income tax benefit		5	4
Depreciation and other items not normalized		(3)	0
Other		(1)	(1)
Total increase (decrease)		1	3
Total income taxes		$ 24	$ 39
Kentucky Utilities Co [Member] | Kentucky tax reform [Member] | Subsequent Event [Member]
Income Taxes [Line Items]
Increase (Decrease) in Regulatory Assets and Liabilities	$ 19