Derivative Instruments and Hedging Activities (Intro) (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Master Netting Arrangements (Numeric) [Line Items]
No or immaterial obligation to return cash collateral obligation under master netting arrangement	$ 0	$ 0
Cash collateral posted under master netting arrangements	9,000,000	21,000,000
LG And E And KU Energy LLC [Member]
Master Netting Arrangements (Numeric) [Line Items]
No or immaterial obligation to return cash collateral obligation under master netting arrangement	0	0
Cash collateral posted under master netting arrangements	9,000,000	21,000,000
Louisville Gas And Electric Co [Member]
Master Netting Arrangements (Numeric) [Line Items]
No or immaterial obligation to return cash collateral obligation under master netting arrangement	0	0
Cash collateral posted under master netting arrangements	9,000,000	21,000,000
Kentucky Utilities Co [Member]
Master Netting Arrangements (Numeric) [Line Items]
No or immaterial obligation to return cash collateral obligation under master netting arrangement	$ 0	$ 0