Commitments and Contingencies - Legal Matters and Regulatory Issues (Details) $ in Millions		3 Months Ended
	Oct. 29, 2018 USD ($)	Mar. 31, 2019 claim resident coal-fired_unit mi	Jun. 01, 2015
Claim By Former Affiliate [Abstract]
Percent of ownership of Talen Energy by Riverstone			35.00%
Amount of alleged improper distribution | $	$ 733
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