Commitments and Contingencies - Legal Matters and Regulatory Issues (Details)	6 Months Ended
	Jun. 30, 2018 claim resident coal-fired_unit mi
LGE [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of residents that filed class action suit | resident	6
Number of miles within plant that would include a class of residents	4
Number of remaining unresolved Clean Air Act violation claims after July 2014 court ruling | claim	1
Generating units retired at the Cane Run plant | coal-fired_unit	3
LGE [Member] | Minimum [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of miles within plant that would include a class of residents	1
LGE [Member] | Maximum [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of miles within plant that would include a class of residents	3
LG And E And KU Energy LLC [Member] | LGE [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of residents that filed class action suit | resident	6
Number of miles within plant that would include a class of residents	4
Number of remaining unresolved Clean Air Act violation claims after July 2014 court ruling | claim	1
Generating units retired at the Cane Run plant | coal-fired_unit	3
LG And E And KU Energy LLC [Member] | LGE [Member] | Minimum [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of miles within plant that would include a class of residents	1
LG And E And KU Energy LLC [Member] | LGE [Member] | Maximum [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of miles within plant that would include a class of residents	3
Louisville Gas And Electric Co [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of residents that filed class action suit | resident	6
Number of miles within plant that would include a class of residents	4
Number of remaining unresolved Clean Air Act violation claims after July 2014 court ruling | claim	1
Generating units retired at the Cane Run plant | coal-fired_unit	3
Louisville Gas And Electric Co [Member] | Minimum [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of miles within plant that would include a class of residents	1
Louisville Gas And Electric Co [Member] | Maximum [Member]
Legal Matters - Cane Run Environmental Claims (Numeric) [Abstract]
Number of miles within plant that would include a class of residents	3