Income and Other Taxes (Credit Carryforwards and Valuation Allowances and Reserves) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Credit carryforwards
Deferred tax asset credit carryforwards	$ 455	$ 256
Tax Cuts And Jobs Act [Member]
Credit carryforwards
Credit Carryforward Valuation Allowance Foreign Tax Credits	122
Taxable Deemed Dividend	462
Deferred Tax Assets, Foreign Tax Credit Carryforwards	205
Permanently reinvested cumulative undistributed foreign earnings	6,000
Valuation Allowances and Reserves (Details) [Roll Forward]
Increase of the valuation allowance as a result of the expected future utilization of foreign tax credits	145
Valuation Allowance Of Deferred Tax Assets [Member]
Valuation Allowances and Reserves (Details) [Roll Forward]
Balance at beginning of period	593	662	$ 622
Additions charged to income	256	17	24
Additions charged to other accounts	0	2	77
Deductions	11	88	61
Balance at end of period	838	593	662
Increase of the valuation allowance as a result of the expected future utilization of foreign tax credits	145
Increase of the valuation allowance as a result of the reduction in the U.S. federal corporate income tax rate	62
Reduction of the valuation allowance as a result of the reduction in the UK statutory income tax rate		(19)	(44)
Valuation Rollforward Specific Transaction Deductions Exchange Rates		65
Investment Tax Credit [Member] | Federal [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	133
Credit Carryforward Valuation Allowance Investment Tax Credit	$ 0
Investment Tax Credit [Member] | Federal [Member] | Minimum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2025
Investment Tax Credit [Member] | Federal [Member] | Maximum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2036
Foreign Tax Credit [Member] | Federal [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	$ 267
Credit Carryforward Valuation Allowance Foreign Tax Credits	(148)
Foreign Tax Credit [Member] | Federal [Member] | Tax Year 2016 [Member] | Tax Cuts And Jobs Act [Member]
Credit carryforwards
Deferred Tax Assets, Foreign Tax Credit Carryforwards	62
Foreign Tax Credit [Member] | Federal [Member] | Tax Year 2017 [Member] | Tax Cuts And Jobs Act [Member]
Credit carryforwards
Deferred Tax Assets, Foreign Tax Credit Carryforwards	$ 205
Foreign Tax Credit [Member] | Federal [Member] | Minimum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2024
Foreign Tax Credit [Member] | Federal [Member] | Maximum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2027
Alternative Minimum Tax Credit [Member] | Federal [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	$ 30
Credit Carryforward Valuation Allowance Alternative Minimum Tax Credit	0
Other [Member] | Federal [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	24
Credit Carryforward Valuation Allowance Other	$ (8)
Other [Member] | Federal [Member] | Minimum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2019
Other [Member] | Federal [Member] | Maximum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2037
Other [Member] | State [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	$ 1
Credit Carryforward Valuation Allowance Other	0
LG And E And KU Energy LLC [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	181	186
LG And E And KU Energy LLC [Member] | Valuation Allowance Of Deferred Tax Assets [Member]
Valuation Allowances and Reserves (Details) [Roll Forward]
Balance at beginning of period	11	12	0
Additions charged to other accounts	4	0	12
Deductions	7	1	0
Balance at end of period	8	$ 11	$ 12
LG And E And KU Energy LLC [Member] | Investment Tax Credit [Member] | Federal [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	133
Credit Carryforward Valuation Allowance Investment Tax Credit	$ 0
LG And E And KU Energy LLC [Member] | Investment Tax Credit [Member] | Federal [Member] | Minimum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2025
LG And E And KU Energy LLC [Member] | Investment Tax Credit [Member] | Federal [Member] | Maximum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2036
LG And E And KU Energy LLC [Member] | Alternative Minimum Tax Credit [Member] | Federal [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	$ 27
Credit Carryforward Valuation Allowance Alternative Minimum Tax Credit	0
LG And E And KU Energy LLC [Member] | Other [Member] | Federal [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	21
Credit Carryforward Valuation Allowance Other	$ (8)
LG And E And KU Energy LLC [Member] | Other [Member] | Federal [Member] | Minimum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2019
LG And E And KU Energy LLC [Member] | Other [Member] | Federal [Member] | Maximum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2037
LG And E And KU Energy LLC [Member] | Other [Member] | State [Member]
Credit carryforwards
Deferred tax asset credit carryforwards	$ 1
Credit Carryforward Valuation Allowance Other	0
Louisville Gas And Electric Co [Member] | Other [Member] | Federal [Member]
Credit carryforwards
Tax Credit Carryforward, Amount	$ 6
Louisville Gas And Electric Co [Member] | Other [Member] | Federal [Member] | Minimum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2034
Louisville Gas And Electric Co [Member] | Other [Member] | Federal [Member] | Maximum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2037
Kentucky Utilities Co [Member] | Other [Member] | Federal [Member]
Credit carryforwards
Tax Credit Carryforward, Amount	$ 6
Kentucky Utilities Co [Member] | Other [Member] | Federal [Member] | Minimum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2034
Kentucky Utilities Co [Member] | Other [Member] | Federal [Member] | Maximum [Member]
Credit carryforwards
Tax Credit Carryforward Expiration Date 1	Dec. 31, 2037