Commitments and Contingencies (Insurance) (Details) $ in Millions	Dec. 31, 2015 USD ($)
Insurance [Abstract]
Maximum obtainable amount of private liability insurance available under Price-Anderson Act	$ 375
Amount of secondary financial protection liability insurance coverage per incident	13,100
Potential Retrospective Assessments Under Secondary Financial Protection System	1,000
Potential Retrospective Assessments Under Secondary Financial Protection System Payable Per Incident Per Year	152
Amount of coverage per occurrence per site for property damage, decontamination and premature decommissioning risks	2,750
Amount Of Sublimit For Non Nuclear Perils Per Occurrence Per Site Under Nuclear Insurance Mutual Companies For Property Damage Decontamination And Premature Decommissioning Risks	1,500
Potential Retrospective Assessment, Limited Insurance Coverage Per Occurrence Per Site, Nuclear Insurance Mutual Companies, Property Damage Decontamination And Premature Decommissioning Risks	187
Seabrook Station Insurance [Member]
Insurance [Abstract]
Potential retrospective assessment recoverable from minority interest for nuclear liability secondary financial protection	15
Potential retrospective assessment recoverable from minority interest for property damage, decontamination and premature decommissioning risks	3
Duane Arnold Energy Center Insurance [Member]
Insurance [Abstract]
Potential retrospective assessment recoverable from minority interest for nuclear liability secondary financial protection	38
Potential retrospective assessment recoverable from minority interest for property damage, decontamination and premature decommissioning risks	5
St Lucie Unit No 2 Insurance [Member]
Insurance [Abstract]
Potential retrospective assessment recoverable from minority interest for nuclear liability secondary financial protection	19
Potential retrospective assessment recoverable from minority interest for property damage, decontamination and premature decommissioning risks	4
FPL [Member]
Insurance [Abstract]
Potential Retrospective Assessments Under Secondary Financial Protection System	509
Potential Retrospective Assessments Under Secondary Financial Protection System Payable Per Incident Per Year	76
Potential Retrospective Assessment, Limited Insurance Coverage Per Occurrence Per Site, Nuclear Insurance Mutual Companies, Property Damage Decontamination And Premature Decommissioning Risks	$ 112