Non-Derivative Fair Value Measurements (Gains and Losses) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities[Line Items]
Decommissioning Fund Investments, Fair Value	$ 7,703	$ 6,880
Special Use Funds Storm Fund Assets	76	74
Debt Securities, Available-for-sale, Amortized Cost	$ 2,009	2,030
Special Use Funds Nuclear Decommissioning Funds Weighted Average Maturity	8 years
Special Use Funds Storm Fund Weighted Average Maturity	1 year
Debt Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Realized gains	$ 110	68	$ 51
Realized losses	70	48	75
Proceeds from sale and maturity of Available-for-sale Securities	2,541	3,005	2,551
Available for sale securities: Special Use Funds - Debt Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Unrealized gains	134	75
Unrealized losses	9	7
Fair Value	201	314
FPL[Member]
Schedule of Available-for-sale Securities[Line Items]
Decommissioning Fund Investments, Fair Value	5,271	4,697
Special Use Funds Storm Fund Assets	76	74
Debt Securities, Available-for-sale, Amortized Cost	$ 1,521	1,523
Special Use Funds Nuclear Decommissioning Funds Weighted Average Maturity	9 years
Special Use Funds Storm Fund Weighted Average Maturity	1 year
FPL[Member] \| Debt Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Realized gains	$ 83	44	31
Realized losses	56	29	49
Proceeds from sale and maturity of Available-for-sale Securities	2,162	2,539	$ 2,100
FPL[Member] \| Available for sale securities: Special Use Funds - Debt Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Unrealized gains	104	58
Unrealized losses	9	7
Fair Value	$ 150	240
Debt Securities [Member] \| FPL[Member] \| Storm Fund [Member]
Schedule of Available-for-sale Securities[Line Items]
Debt Securities, Available-for-sale, Term	1 year
Equity Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
marketable securities, unrealized gain (loss) recognized during the period on securities still held	$ 627	780
Equity Securities [Member] \| FPL[Member]
Schedule of Available-for-sale Securities[Line Items]
marketable securities, unrealized gain (loss) recognized during the period on securities still held	$ 444	$ 510
Weighted Average [Member] \| Nuclear Decommissioning Funds [Member]
Schedule of Available-for-sale Securities[Line Items]
Debt Securities, Available-for-sale, Term
Weighted Average [Member] \| FPL[Member] \| Nuclear Decommissioning Funds [Member]
Schedule of Available-for-sale Securities[Line Items]
Debt Securities, Available-for-sale, Term
Weighted Average [Member] \| FPL[Member] \| Storm Fund [Member]
Schedule of Available-for-sale Securities[Line Items]
Debt Securities, Available-for-sale, Term	1 year

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