Commitments and Contingencies - Legal Matters and Regulatory Issues (Details) $ in Millions		1 Months Ended			12 Months Ended
	Nov. 30, 2014 USD ($)	Jun. 30, 2017 mi	Jul. 31, 2014 claim	Dec. 31, 2013 resident mi	Dec. 31, 2015 coal-fired_unit	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