Impairment of Long-lived Assets (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended
	Jun. 30, 2013 employees	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2012 FES	Jun. 30, 2012 FES	Jun. 30, 2013 Excessive Inventories	Jun. 30, 2013 Long-Lived Assets to be Abandoned, Total employees	Jun. 30, 2013 Hatfield's Ferry, Units 1-3 Pollution Control Bond After termination of operations AE Supply	Jul. 08, 2013 Subsequent Event Hatfield's Ferry, Units 1-3 MW	Jul. 08, 2013 Subsequent Event Mitchell, Units 2-3 MW
Schedule of Generating Plant Retirements [Line Items]
Plant Capacity										1,710	370
Asset Impairment Charges	$ 473,000,000		$ 473,000,000	$ 0			$ 13,000,000
Restructuring and Related Cost, Expected Number of Positions Eliminated (in employees)	380							250
Severance Costs	15,000,000	10,000,000		17,000,000	6,000,000	10,000,000
Debt Instrument, Face Amount									235,000,000
Severance Costs, Expected in Next Fiscal Quarter								$ 3,000,000