Commitments and Contingencies (Environmental Matters and Other) (Details)	9 Months Ended
	Sep. 30, 2015 USD ($) phase category
Environmental Matters - Domestic - Air - Cross State Air Pollution Rule (Numeric) [Abstract]
Number of phases CSAPR will be implemented | phase	2
Environmental Matters - Domestic - Water/Waste - Coal Combustion Residuals (CCRs) [Abstract]
Minimum range in years to complete closure requirements for CCRs under certain events	3 years
Maximum range in years to complete closure requirements for CCRs under certain events	10 years
Increase to existing AROs	$ 36,000,000
Environmental Matters - Domestic - Water/Waste - Seepages and Groundwater Infiltration - Pennsylvania, Montana (Numeric) [Abstract]
Period for PPL Montana to provide financial assurance to Montana Department of Environmental Quality (in years)	5 years
Environmental Matters - Waters of the United States (WOTUS) [Abstract]
Number of categories identified | category	6
Number of categories identified to be determined on case-by-case basis | category	2
Other - Nuclear Insurance (Numeric) [Abstract]
Maximum public liability for claims resulting an incident at nuclear station	$ 13,300,000,000
Maximum amount that could be assessed resulting from an incident at nuclear station	255,000,000
Maximum amount payable per year resulting from an incident at nuclear station	38,000,000
Maximum amount of insured property damage losses at nuclear station	2,000,000,000
Maximum assessment for retroactive premiums for nuclear outage insurance coverage	$ 55,000,000
Minimum
Environmental Matters - Domestic - Air - Mercury and Air Toxics Standards (Numeric) [Abstract]
Possible period of extension to comply with final mercury and air toxics standards	1 year
Maximum
Environmental Matters - Domestic - Air - Mercury and Air Toxics Standards (Numeric) [Abstract]
Possible period of extension to comply with final mercury and air toxics standards	2 years