Taxes (Details 5) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	$ 15,800
State Jurisdiction [Member]
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	14,149
State Jurisdiction [Member] | 2013-2017
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	9
State Jurisdiction [Member] | 2018-2022
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	2,907
State Jurisdiction [Member] | 2023-2027
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	6,505
State Jurisdiction [Member] | 2028-2032
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	4,728
Local Jurisdiction [Member]
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	1,665
Local Jurisdiction [Member] | 2013-2017
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	1,665
Local Jurisdiction [Member] | 2018-2022
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
Local Jurisdiction [Member] | 2023-2027
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
Local Jurisdiction [Member] | 2028-2032
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
FES | State Jurisdiction [Member]
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	834
FES | State Jurisdiction [Member] | 2013-2017
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
FES | State Jurisdiction [Member] | 2018-2022
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	43
FES | State Jurisdiction [Member] | 2023-2027
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	45
FES | State Jurisdiction [Member] | 2028-2032
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	746
FES | Local Jurisdiction [Member]
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	904
FES | Local Jurisdiction [Member] | 2013-2017
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	904
FES | Local Jurisdiction [Member] | 2018-2022
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
FES | Local Jurisdiction [Member] | 2023-2027
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
FES | Local Jurisdiction [Member] | 2028-2032
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	$ 0