Financing Activities (Distributions and Capital Contributions) (Details) - USD ($) $ / shares in Units, $ in Billions	1 Months Ended		3 Months Ended								12 Months Ended
	Feb. 28, 2018	Nov. 30, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Distributions [Line Items]
Dividend payable date of quarterly common stock dividend		Jan. 02, 2018
Current quarterly common stock dividend (in dollars per share)		$ 0.395	$ 0.3950	$ 0.3950	$ 0.3950	$ 0.3950	$ 0.38	$ 0.38	$ 0.38	$ 0.38	$ 1.58	$ 1.52	$ 1.50
Annualized current quarterly common stock dividend (in dollars per share)		$ 1.58
Subsequent Event [Member]
Distributions [Line Items]
Current quarterly common stock dividend (in dollars per share)	$ 0.410
Annualized current quarterly common stock dividend (in dollars per share)	$ 1.64
LKE [Member]
Distributions [Line Items]
Restricted net assets at end of period			$ 2.7								$ 2.7
Unrestricted assets at the end of period			3.1								$ 3.1
Minimum adjusted equity to total capitalization in order to pay dividends											30.00%
LG And E And KU Energy LLC [Member]
Distributions [Line Items]
Restricted net assets at end of period			2.7								$ 2.7
Unrestricted assets at the end of period			3.1								$ 3.1
Minimum adjusted equity to total capitalization in order to pay dividends											30.00%
Louisville Gas And Electric Co [Member]
Distributions [Line Items]
Restricted net assets at end of period			1.1								$ 1.1
Unrestricted assets at the end of period			1.4								$ 1.4
Minimum adjusted equity to total capitalization in order to pay dividends											30.00%
Kentucky Utilities Co [Member]
Distributions [Line Items]
Restricted net assets at end of period			1.6								$ 1.6
Unrestricted assets at the end of period			$ 1.7								$ 1.7
Minimum adjusted equity to total capitalization in order to pay dividends											30.00%