Derivative Instruments (Net Notional Volumes and Additional Disclosures) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015 MWh	Dec. 31, 2014 MWh
Commodity contract - Power [Member]
Derivative [Line Items]
Non-monetary net notional volumes	(103,000,000)	(73,000,000)
Commodity contract - Natural gas [Member]
Derivative [Line Items]
Non-monetary net notional volumes	1,458,000,000	1,436,000,000
Commodity contract - Oil [Member]
Derivative [Line Items]
Non-monetary net notional volumes	(9,000,000)	(11,000,000)
Interest rate contracts [Member]
Derivative [Line Items]
Notional amount	7,100	7,400
Currency Swap [Member]
Derivative [Line Items]
Notional amount	693	661
FPL [Member] | Commodity contract - Power [Member]
Derivative [Line Items]
Non-monetary net notional volumes	0	0
FPL [Member] | Commodity contract - Natural gas [Member]
Derivative [Line Items]
Non-monetary net notional volumes	892,000,000	845,000,000
FPL [Member] | Commodity contract - Oil [Member]
Derivative [Line Items]
Non-monetary net notional volumes	0	0