Commitments and Contingencies (Energy Purchases, Energy Sales, Other Commitments, Legal Matters and Regulatory Issues) (Details) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2013 Integer MW	Sep. 30, 2012
Energy Purchase Commitments (Numeric) [Abstract]
Pre-tax charges incurred from coal contract modifications	$ 17,000,000		$ 29,000,000
Frequency of competitive solicitations each plan year		twice
Shortest term of layered short-term full requirement products (in months)		3
Longest term of layered short-term full requirement products (in months)		12
Recurring term of spot market product (in months)		12
Number of competitive solicitations completed to date under the Public Utility Commission approved purchase plan		2
Total number of competitive solicitations under the Public Utility Commission approved purchase plan		4
Legal Matters - Sierra Club Litigation (Numeric) [Abstract]
Number of separate claims included in the complaint against PPL Montana		39
Number of claims against Colstrip that did not allege Prevention of Significant Deterioration but alleged Title V operating permit violations		3
Average requested amount, per day per violation, of injuctive relief and civil penalities		36,000
Amount of civil penalities to be used for beneficial mitigation projects		100,000
Regulatory Issues - Maryland Capacity Order (Numeric) [Abstract]
Number electric utilities ordered to enter into long term contracts		3
Capacity of natural gas-fired combined-cycle generating facility (in MW)		661
Regulatory Issues - Pacific Northwest Markets (Numeric) [Abstract]
Amount for claims remaining unsettled at period end		50,000,000
Settlement amount reached with one of the parties		75,000
Amount of claim sought by City of Tacoma		23,000,000
Regulatory Issues - Electric - Reliability Standards (Numeric) [Abstract]
Maximum per day penalties for reliability violations		1,000,000
PPL Energy Supply LLC [Member]
Energy Purchase Commitments (Numeric) [Abstract]
Pre-tax charges incurred from coal contract modifications	17,000,000		29,000,000
Legal Matters - Sierra Club Litigation (Numeric) [Abstract]
Number of separate claims included in the complaint against PPL Montana		39
Number of claims against Colstrip that did not allege Prevention of Significant Deterioration but alleged Title V operating permit violations		3
Average requested amount, per day per violation, of injuctive relief and civil penalities		36,000
Amount of civil penalities to be used for beneficial mitigation projects		100,000
Regulatory Issues - Maryland Capacity Order (Numeric) [Abstract]
Number electric utilities ordered to enter into long term contracts		3
Capacity of natural gas-fired combined-cycle generating facility (in MW)		661
Regulatory Issues - Pacific Northwest Markets (Numeric) [Abstract]
Amount for claims remaining unsettled at period end		50,000,000
Settlement amount reached with one of the parties		75,000
Amount of claim sought by City of Tacoma		23,000,000
Regulatory Issues - Electric - Reliability Standards (Numeric) [Abstract]
Maximum per day penalties for reliability violations		1,000,000
PPL Electric Utilities Corp [Member]
Energy Purchase Commitments (Numeric) [Abstract]
Frequency of competitive solicitations each plan year		twice
Shortest term of layered short-term full requirement products (in months)		3
Longest term of layered short-term full requirement products (in months)		12
Recurring term of spot market product (in months)		12
Number of competitive solicitations completed to date under the Public Utility Commission approved purchase plan		2
Total number of competitive solicitations under the Public Utility Commission approved purchase plan		4
Regulatory Issues - Maryland Capacity Order (Numeric) [Abstract]
Number electric utilities ordered to enter into long term contracts		3
Capacity of natural gas-fired combined-cycle generating facility (in MW)		661
Regulatory Issues - Electric - Reliability Standards (Numeric) [Abstract]
Maximum per day penalties for reliability violations		1,000,000
LG And E And KU Energy LLC [Member]
Regulatory Issues - Electric - Reliability Standards (Numeric) [Abstract]
Maximum per day penalties for reliability violations		1,000,000
Louisville Gas And Electric Co [Member]
Regulatory Issues - Electric - Reliability Standards (Numeric) [Abstract]
Maximum per day penalties for reliability violations		1,000,000
Kentucky Utilities Co [Member]
Regulatory Issues - Electric - Reliability Standards (Numeric) [Abstract]
Maximum per day penalties for reliability violations		$ 1,000,000