Derivative Instruments (Net Notional Volumes and Additional Disclosures) (Details) bbl in Millions, MWh in Millions, MMBTU in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) MWh MMBTU bbl	Dec. 31, 2018 USD ($) MWh MMBTU bbl
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount | $	$ 8,900	$ 13,400
Currency Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount | $	$ 1,000	$ 656
Short [Member] | Commodity contract - Power [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Derivative, Nonmonetary Notional Amount | MWh	81	100
Short [Member] | Commodity contract - Natural gas [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	1,723	491
Short [Member] | Commodity contract - Oil [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Derivative, Nonmonetary Notional Amount, Volume | bbl	13	30
Short [Member] | FPL[Member] | Commodity contract - Oil [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Derivative, Nonmonetary Notional Amount, Volume | bbl	0	0
Long [Member] | FPL[Member] | Commodity contract - Power [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Derivative, Nonmonetary Notional Amount | MWh	1	1
Long [Member] | FPL[Member] | Commodity contract - Natural gas [Member]
Schedule of net notional volume of commodity derivative instruments [Abstract]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	161	231