Derivative Instruments and Hedging Activities (Intro) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 MW	Dec. 31, 2012
Master Netting Arrangements Numeric [Line Items]
Obligation to return cash collateral obligation under master netting arrangement	$ 14	$ 112
Cash collateral posted under master netting arrangements	22	32
Commodity Price Risk Nontrading [Line Items]
Baseload generation fleet capacity (in MW)	7,298
Intermediate and peaking generation fleet capacity (in MW)	3,316
Commodity Price Risk (Non-trading) - Cash Flow Hedges (Numeric) [Abstract]
Net unrealized after-tax gains (losses) expected to be reclassified into earnings within 12 months related to commodity price risk cash flow hedge contracts	47
No or insignificant amounts previously recorded in AOCI reclassified to earnings related to commodity price risk cash flow hedge contracts	For the three and nine months ended September 30, 2013 and 2012, such reclassifications were insignificant.
No or immaterial hedge ineffectiveness related to commodity price risk cash flow hedge contracts	For the three and nine months ended September 30, 2013 and 2012, hedge ineffectiveness associated with energy derivatives was insignificant.
Commodity Price Risk (Non-trading) - Economic Activity (Numeric) [Abstract]
Year of expiration of the maximum maturity date of economic activity derivative contracts	2019
PPL Energy Supply LLC [Member]
Master Netting Arrangements Numeric [Line Items]
Obligation to return cash collateral obligation under master netting arrangement	14	112
Commodity Price Risk Nontrading [Line Items]
Baseload generation fleet capacity (in MW)	7,298
Intermediate and peaking generation fleet capacity (in MW)	3,316
Commodity Price Risk (Non-trading) - Cash Flow Hedges (Numeric) [Abstract]
Net unrealized after-tax gains (losses) expected to be reclassified into earnings within 12 months related to commodity price risk cash flow hedge contracts	47
No or insignificant amounts previously recorded in AOCI reclassified to earnings related to commodity price risk cash flow hedge contracts	For the three and nine months ended September 30, 2013 and 2012, such reclassifications were insignificant.
No or immaterial hedge ineffectiveness related to commodity price risk cash flow hedge contracts	For the three and nine months ended September 30, 2013 and 2012, hedge ineffectiveness associated with energy derivatives was insignificant.
Commodity Price Risk (Non-trading) - Economic Activity (Numeric) [Abstract]
Year of expiration of the maximum maturity date of economic activity derivative contracts	2019
LG And E And KU Energy LLC [Member]
Master Netting Arrangements Numeric [Line Items]
Cash collateral posted under master netting arrangements	22	32
Louisville Gas And Electric Co [Member]
Master Netting Arrangements Numeric [Line Items]
Cash collateral posted under master netting arrangements	$ 22	$ 32