Capitalization (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Schedule of Capitalization [Line Items]
Aggregate LOC Amount	639
FGCO
Schedule of Capitalization [Line Items]
Aggregate LOC Amount	365
FGCO | Minimum
Schedule of Capitalization [Line Items]
Annual Fees	1.71%
FGCO | Maximum
Schedule of Capitalization [Line Items]
Annual Fees	3.30%
NGC
Schedule of Capitalization [Line Items]
Aggregate LOC Amount	200
Annual Fees	1.71%
Met-Ed
Schedule of Capitalization [Line Items]
Aggregate LOC Amount	29
Annual Fees	1.75%
Penelec
Schedule of Capitalization [Line Items]
Aggregate LOC Amount	45
Penelec | Minimum
Schedule of Capitalization [Line Items]
Annual Fees	1.71%
Penelec | Maximum
Schedule of Capitalization [Line Items]
Annual Fees	1.75%