Derivative Instruments (Income Statement Disclosure) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Gains (losses) related to derivatives not designated as hedging instruments	$ 80	$ 153	$ 551
Not Designated as Hedging Instrument [Member] | Commodity contracts [Member] | Gains (Losses) Included In Operating Revenues [Member]
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Gains (losses) related to derivatives not designated as hedging instruments	377	454	459
Not Designated as Hedging Instrument [Member] | Commodity contracts [Member] | Gains (Losses) Included In Fuel, Purchased Power And Interchange [Member]
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Gains (losses) related to derivatives not designated as hedging instruments	(2)	0	(1)
Not Designated as Hedging Instrument [Member] | Foreign currency contracts [Member] | Gain (loss) included in interest expense [Member]
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Gains (losses) related to derivatives not designated as hedging instruments	19	55	14
Not Designated as Hedging Instrument [Member] | Foreign currency contracts [Member] | Gains (Losses) Included In Other - Net [Member]
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Gains (losses) related to derivatives not designated as hedging instruments	0	(4)	(1)
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Gain (loss) included in interest expense [Member]
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Gains (losses) related to derivatives not designated as hedging instruments	(280)	(223)	181
Reclassification out of Accumulated Other Comprehensive Income [Member] | Not Designated as Hedging Instrument [Member] | Foreign currency contracts [Member] | Gain (loss) included in interest expense [Member]
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Interest Expense	(4)	(81)	(11)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Gain (loss) included in interest expense [Member]
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Interest Expense	(30)	(48)	(90)
FPL[Member]
Gains (losses) related to derivatives not designated as hedging instruments [Abstract]
Gains (losses) on commodity contracts, recorded as regulatory assets and or liabilities on the balance sheet due to regulatory treatment	$ (31)	$ (169)	$ 203