Regulatory Matters (Details) (USD $)	12 Months Ended	1 Months Ended	12 Months Ended		12 Months Ended				0 Months Ended	12 Months Ended	0 Months Ended			31 Months Ended	12 Months Ended				1 Months Ended	3 Months Ended	12 Months Ended		36 Months Ended			12 Months Ended							12 Months Ended									1 Months Ended	12 Months Ended			1 Months Ended		12 Months Ended	1 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2012 entities	Apr. 30, 2007 FERC kv	Dec. 31, 2012 FERC class	Jan. 21, 2010 FERC issues	Dec. 31, 2012 FERC MOPR Reform	Dec. 07, 2012 FERC MOPR Reform exemption	Dec. 20, 2012 FERC Synchronous Condensers	Dec. 31, 2012 FERC PJM	Aug. 24, 2012 FERC PATH	Dec. 31, 2012 FERC PATH kv	Aug. 24, 2012 FERC PATH-Allegheny	Aug. 24, 2012 FERC Path-WV	Jun. 30, 2011 FERC Path-WV challenge	Dec. 31, 2012 FERC FES and AE FTR Underfunding Complaint Minimum	Dec. 31, 2012 MARYLAND	Dec. 31, 2008 MARYLAND	Aug. 31, 2011 MARYLAND	Oct. 06, 2009 MARYLAND	Aug. 31, 2011 OHIO proposals	Oct. 31, 2009 OHIO proposals	Dec. 31, 2012 OHIO plan	Dec. 31, 2009 OHIO	Dec. 31, 2012 OHIO plan	Dec. 31, 2011 OHIO	Dec. 31, 2010 OHIO	Dec. 31, 2012 OHIO Year 2012 MWh	Dec. 31, 2012 OHIO Year 2013 MWh	Dec. 31, 2012 OHIO Year 2014 MWh	Dec. 31, 2012 OHIO Annually Through 2025 MWh	Dec. 31, 2012 OHIO Annually Through 2018	Nov. 30, 2012 New Jersey	Feb. 22, 2013 New Jersey Subsequent Event	Dec. 31, 2012 PENNSYLVANIA smart_meter Party	Dec. 31, 2010 PENNSYLVANIA	Dec. 31, 2011 PENNSYLVANIA Party	May 31, 2011 PENNSYLVANIA	Apr. 29, 2011 PENNSYLVANIA questions	Dec. 31, 2012 PENNSYLVANIA Statutory Penalty	Dec. 31, 2012 PENNSYLVANIA Year 2013	Feb. 15, 2013 PENNSYLVANIA Subsequent Event choice	Jan. 16, 2013 PENNSYLVANIA Subsequent Event issues Party	Apr. 30, 2010 WEST VIRGINIA	Dec. 31, 2012 WEST VIRGINIA MW	Oct. 22, 2012 WEST VIRGINIA hearing	Feb. 28, 2011 WEST VIRGINIA Facilities	Feb. 28, 2011 WEST VIRGINIA City of New Martinsville entities	Feb. 28, 2011 WEST VIRGINIA Morgantown Energy entities	Dec. 31, 2013 WEST VIRGINIA Forecast	Oct. 31, 2006 California Claims Matters FERC Proceedings	Dec. 31, 2012 California Claims Matters FERC	Dec. 31, 2012 Yards Creek Pumped Storage Project FERC MW	Dec. 31, 2012 Yards Creek Pumped Storage Project FERC JCP&L	Dec. 31, 2012 The Seneca Pumped Storage Project FERC MW	Dec. 31, 2012 The Seneca Pumped Storage Project Relicensing
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
Recovery period for expenditures for cost recovery program															3 years	6 years
Maximum penalty assessed, in dollars per day per violation															25,000
Expected increase in cost due to proposed plan															106,000,000
Requested increase in revenues																															31,500,000	603,000,000
Increase in revenue recovery request																																112,000,000
Number of cost recovery choices																																								2
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
ESP extension term																					2 years
Generation supply auction period, after approval																					3 years
Generation supply auction period, before approval																					1 year
Annual energy savings																										1,211,000	1,726,000	2,306,000	2,903,000
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
Number of plans																					3		3
Portfolio plan, estimated cost																					250,000,000		250,000,000
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%
Loss contingency, maximum																																						20,000,000
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
Number of parties not settled																																									1
Number of issues not settled																																									1
Expected Cost of Meter Installations																																	1,250,000,000
Annualized base rate increase																																										40,000,000
Storm restoration deferral period																																										5 years
Number of public hearings held																																												2
Period of time to implement plan																																											6 months
Period of time to file case																																											6 months
Additional base rate increase																																										20,000,000
Decrease in ENEC rates																																										20,000,000
Number of electric generation facilities																																													3
Number of electric generation facilities, owned by third party																																														1	1
Forecast over energy recovery																																																66,000,000
Forecast over energy recovery offset																																																66,000,000
Resource plan, proposed transfer																																											1,476
Annual load growth rate																																											1.40%
Regional enforcement entities	8
Power threshold for cost methodology		500
Denied Recovery Charges of Exit Fees			78,800,000
Identified issues for written comments				9
Hybrid methodology, beneficiary pays cost allocation								50.00%
Hybrid methodology, postage stamp cost allocation								50.00%
Annual Revenue requirements in Zone			16,000,000
Number of classes of regulatory proceedings			2
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
Cost recovery, PP&E reclassified to Regulatory Assets											62,000,000	59,000,000
Return on equity for cost recovery									10.90%
Base return on equity for cost recovery									10.40%
Return on equity for cost recovery from RTO membership									0.50%
Remaining Recovery Period of Regulatory Assets									5 years
Number of Formal Challenges													2
Hydroelectric project																																																			400		451
Asset Transfer, Price							21,500,000
Ownership interest																																																				50.00%
Renewal length of operating license																																																				40 years
ILP licensure period																																																				5 years
Period of cycle																																																						5 years
Number of Exemptions Added						2
Deadline to Reply to Federal Authority					30 days
Estimated Conversion Costs							60,000,000
Revenues Lost of Which the Entity is Entitled														$ 55,000,000