Derivative Instruments and Hedging Activities - Intro (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Master Netting Arrangements (Numeric) [Line Items]
Cash Collateral Obligation Under Master Netting Arrangement	$ 13	$ 19
Cash collateral posted under master netting arrangements	2	3
LG And E And KU Energy LLC [Member]
Master Netting Arrangements (Numeric) [Line Items]
Cash Collateral Obligation Under Master Netting Arrangement	0	0
Cash collateral posted under master netting arrangements	2	3
Louisville Gas And Electric Co [Member]
Master Netting Arrangements (Numeric) [Line Items]
Cash Collateral Obligation Under Master Netting Arrangement	0	0
Cash collateral posted under master netting arrangements	$ 2	$ 3