Derivative Instruments and Hedging Activities (Intro) (Details) - USD ($) $ in Millions |
Mar. 31, 2016 |
Dec. 31, 2015 |
---|---|---|
Master Netting Arrangements (Numeric) [Line Items] | ||
Obligation to return cash collateral obligation under master netting arrangement | $ 15 | |
Cash collateral posted under master netting arrangements | 8 | $ 9 |
LG And E And KU Energy LLC [Member] | ||
Master Netting Arrangements (Numeric) [Line Items] | ||
Cash collateral posted under master netting arrangements | 8 | 9 |
Louisville Gas And Electric Co [Member] | ||
Master Netting Arrangements (Numeric) [Line Items] | ||
Cash collateral posted under master netting arrangements | $ 8 | $ 9 |