Commitments and Contingencies (Energy Purchases, Energy Sales, Other Commitments and Legal Matters) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 30, 2012 Integer MW	Mar. 31, 2012 Integer	Dec. 31, 2011	May 07, 2012 Integer
Energy Purchase Commitments (Numeric) [Abstract]
Number of competitive solicitations conducted to date under the June 2009 PUC-approved purchase plan for PLR supply after 2010				11
Total number of competitive solicitations to be conducted under June 2009 PUC-approved purchase plan for PLR supply requirements after 2010		14
Shortest term, in months, of PPL Electric PLR solicitations		5
Longest term, in years, of PPL Electric PLR solicitations		10
Legal Matters - Montana Hydroelectric Litigation (Numeric) [Abstract]
Amount of compensation awarded in 2008 by the Montana District Court regarding PPL Montana's use of navigable riverbeds for periods 2000 to 2006		$ 35
Amount of compensation awarded in 2008 by the Montana District Court regarding PPL Montana's use of navigable riverbeds for 2007		6
Interest rate per year		10.00%
Contingency reversal during period, pre-tax			89
Contingency reversal during period, after-tax			53
Legal Matters - Bankruptcy of Southern Montana Electric Generation and Transmission Cooperative, Inc. (Numeric) [Abstract]
Reserve related to the accounts receivable from a bankrupt counterparty		22
Regulatory Issues - FERC Market-Based Rate Authority (Numeric) [Abstract]
Time from December 1998 that a subsidiary was required to respond to the FERC market analysis information request (in years)		3
Frequency, after initial filing, that a subsidiary is required to respond to the FERC market analysis information request (in years)		3
Regulatory Issues - Energy Policy Act of 2005 - Reliability Standards (Numeric) [Abstract]
Maximum per day penalties for reliability violations		$ 1
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