Regulatory Matters (Details) (USD $)	0 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended			6 Months Ended				6 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	30 Months Ended	36 Months Ended		6 Months Ended			6 Months Ended	12 Months Ended				1 Months Ended			1 Months Ended			6 Months Ended	3 Months Ended	6 Months Ended											6 Months Ended			6 Months Ended
	Dec. 09, 2008	Jun. 30, 2012 entities	Apr. 30, 2007 FERC kv	Jun. 30, 2012 FERC	Jan. 21, 2010 FERC issues	Jun. 30, 2012 FERC PJM	Jun. 30, 2012 FERC PATH kv	Dec. 28, 2011 FERC PJM Calculation Error	Dec. 28, 2011 FERC PJM Calculation Error FES	Dec. 28, 2011 FERC PJM Calculation Error AE Supply	Jun. 30, 2012 The Seneca Pumped Storage Project Relicensing	Aug. 31, 2011 OHIO proposals	Oct. 31, 2009 OHIO proposals	Jun. 30, 2012 OHIO	Dec. 31, 2009 OHIO	Jun. 30, 2012 OHIO	Dec. 31, 2011 OHIO	Dec. 31, 2010 OHIO	Jun. 30, 2012 MARYLAND	Aug. 31, 2011 MARYLAND	Oct. 06, 2009 MARYLAND	Jun. 30, 2012 PENNSYLVANIA smart_meter	Dec. 31, 2010 PENNSYLVANIA	Jun. 30, 2011 PENNSYLVANIA Party	May 31, 2011 PENNSYLVANIA	Apr. 29, 2011 PENNSYLVANIA questions	Apr. 30, 2010 WEST VIRGINIA	Feb. 28, 2011 WEST VIRGINIA Facilities	Jan. 31, 2011 WEST VIRGINIA Facilities	Feb. 28, 2011 WEST VIRGINIA City of New Martinsville entities	Feb. 28, 2011 WEST VIRGINIA Morgantown Energy entities	Oct. 31, 2006 California Claims Matters FERC Proceedings	Jun. 30, 2012 California Claims Matters FERC	Jun. 30, 2012 Yards Creek Pumped Storage Project FERC MW	Jun. 30, 2012 Yards Creek Pumped Storage Project FERC JCP&L	Jun. 30, 2012 The Seneca Pumped Storage Project FERC MW	Jun. 30, 2012 Year 2014 [Member] OHIO GWh	Jun. 30, 2012 Annually Through 2025 [Member] OHIO GWh	Jun. 30, 2012 Annually Through 2018 [Member] OHIO	Jun. 30, 2012 Year 2012 OHIO GWh MWh	Jun. 30, 2012 Year 2013 OHIO GWh	Jun. 30, 2012 Year 2013 PENNSYLVANIA	Jun. 30, 2012 Delivery Year 2011-2012 [Member] FERC PJM Calculation Error	Jun. 30, 2012 Delivery Year 2011-2012 [Member] FERC PJM Calculation Error FES	Jun. 30, 2012 Delivery Year 2011-2012 [Member] FERC PJM Calculation Error AE Supply	Jun. 30, 2012 Supporting Application OHIO Party	Jun. 30, 2012 Not Opposing Application OHIO Party	Jul. 13, 2012 Plant Deactivation WEST VIRGINIA plant	Jun. 30, 2012 FTR Allocation Complaint FERC PJM
Regulatory Matters [Line Items]
Proposed electric consumption reduction percentage																			10.00%
Proposed electric demand reduction percentage																			15.00%
Expenditures for cost recovery program																				$ 66,000,000	$ 101,000,000
Maximum penalty assessed, in dollars per day per violation																			25,000
Recovery period for expenditures for cost recovery program																				3 years	6 years
Load cap percentage minimum														80.00%
Maximum trance award to a single supplier														80.00%
Generation discount for low income customers														6.00%
Costs avoided by customers, integration period														5 years
Costs avoided by customers														360,000,000
Fund to assist low income customers														12,000,000
Legal Parties																																														19	7
ESP extension term														2 years
Generation supply auction period, after approval														3 years
Generation supply auction period, before approval														1 year
Annual energy savings																																					2,306	2,903		1,211	1,726
Increase (decrease) in annual energy savings																																								416,000
Utilities required to reduce peak demand															1.00%
Utilities required to additionally reduce peak demand																																							0.75%
Period of the portfolio plans filed seeking approval for the program															3 years
Load served from renewable energy resources																2.00%	1.50%	1.00%
Request for proposals conducted												2	2
Marginal transmission refund period																						29 months
Marginal transmission losses																							254,000,000
Minimum reduction in Utilities reduce energy consumption																									1.00%																	3.00%
Minimum reduction in Utilities peak demand																																										4.50%
Target installation smart meter																						25,000
Grace period																						30 months
Expenditure amortization period																						10 years
Parties able to challenge recovery amounts																								1
Directed questions for investigation																										11
Annualized base rate increase																											40,000,000
Storm restoration deferral period																											5 years
Compliance Filing, Period																																																	60 days
Additional base rate increase																											20,000,000
Decrease in ENEC rates																											20,000,000
Facilities seeking certification as qualified energy resource facilities																													3
Number of electric generation facilities																												3
Number of electric generation facilities, owned by third party																														1	1
Number of approved plant deactivations																																																3
Power threshold for cost methodology			500
Identified issues for written comments					9
Hybrid methodology, postage stamp cost allocation						50.00%
Hybrid methodology, beneficiary pays cost allocation						50.00%
One time payment, ATSI agreed to MISO				1,800,000
Annual Revenue requirements in Zone				15,000,000
Losses incurred due to underfunding of contracts								35,000,000	500,000	34,500,000																																	11,500,000	11,400,000	100,000
Settlement proposal claims																																	$ 190,000,000
Court proceedings from filed claims																																1
New Voltage transmission facilities across PJM and a zonal transmission rate (In KV)							765
Hydroelectric project																																		400		451
Ownership interest																																			50.00%
Renewal length of operating license																																			40 years
ILP licensure period																																			5 years
Period of cycle											5 years
Regional enforcement entities		8
Customer Power Loss Period	11 hours