Taxes (Details 5) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	$ 9,900
2015-2019
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	63
State Jurisdiction
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	6,752
State Jurisdiction | 2020-2024
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	1,813
State Jurisdiction | 2025-2029
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	1,704
State Jurisdiction | 2030-2034
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	3,172
Local Jurisdiction
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	3,170
Local Jurisdiction | 2015-2019
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	2,524
Local Jurisdiction | 2020-2024
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	646
Local Jurisdiction | 2025-2029
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
Local Jurisdiction | 2030-2034
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
FES | State Jurisdiction
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	1,271
FES | State Jurisdiction | 2015-2019
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
FES | State Jurisdiction | 2020-2024
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	182
FES | State Jurisdiction | 2025-2029
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	88
FES | State Jurisdiction | 2030-2034
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	1,001
FES | Local Jurisdiction
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	1,874
FES | Local Jurisdiction | 2015-2019
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	1,874
FES | Local Jurisdiction | 2020-2024
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
FES | Local Jurisdiction | 2025-2029
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	0
FES | Local Jurisdiction | 2030-2034
Pre-tax net operating loss expiration period
Pre-tax net operating loss carryforwards for state and local income tax purposes	$ 0