Derivative Instruments and Hedging Activities - Intro (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Master Netting Arrangements (Numeric) [Line Items]
Cash colleteral posted under master netting arrangements	$ 22	$ 0
LG And E And KU Energy LLC [Member]
Master Netting Arrangements (Numeric) [Line Items]
Cash collateral obligation under master netting arrangements	0	0
Cash colleteral posted under master netting arrangements	0	0
Louisville Gas And Electric Co [Member]
Master Netting Arrangements (Numeric) [Line Items]
Cash collateral obligation under master netting arrangements	0	0
Cash colleteral posted under master netting arrangements	0	0
Kentucky Utilities Co [Member]
Master Netting Arrangements (Numeric) [Line Items]
Cash collateral obligation under master netting arrangements	0	0
Cash colleteral posted under master netting arrangements	$ 0	$ 0