Derivative Instruments (Net Notional Volumes and Additional Disclosures) (Details) bbl in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	Dec. 31, 2017 USD ($) MWh MMBTU bbl	Dec. 31, 2016 USD ($) MWh MMBTU bbl
Interest Rate Swap [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Notional Amount of Foreign Currency Cash Flow Hedge Derivatives | $	$ 12,100	$ 15,100
Currency Swap [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Notional Amount of Foreign Currency Cash Flow Hedge Derivatives | $	$ 718	$ 705
FPL[Member] | Commodity contract - Power [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Non monetary net notional volumes | MWh	0	0
FPL[Member] | Commodity contract - Natural gas [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Non monetary net notional volumes	(142)	(618)
FPL[Member] | Commodity contract - Oil [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Non monetary net notional volumes | bbl	0	0
Short [Member] | Commodity contract - Power [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Non monetary net notional volumes | MWh	(109)	(84)
Short [Member] | Commodity contract - Natural gas [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Non monetary net notional volumes	(74)
Short [Member] | Commodity contract - Oil [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Non monetary net notional volumes | bbl	(15)	(7)
Long [Member] | Commodity contract - Natural gas [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Non monetary net notional volumes		(1,002)