Fair Value Measurements (Gains and Losses on Available-for-sale Debt Securities) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Debt Securities [Member]
Marketable Securities, Available-for-sale [Line Items]
Realized Gains	$ 26	$ 17	$ 56	$ 25
Realized Losses	16	11	33	20
Proceeds from sale or maturity of securities	753	788	1,491	1,475
Available for sale securities: Special Use Funds - Debt Securities [Member]
Marketable Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	125		125		$ 75
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	29		29		7
Fair value of available for sale securities in an unrealized loss position	289		289		314
FPL [Member] \| Debt Securities [Member]
Marketable Securities, Available-for-sale [Line Items]
Realized Gains	20	9	45	15
Realized Losses	13	5	28	9
Proceeds from sale or maturity of securities	665	$ 685	1,272	$ 1,227
FPL [Member] \| Available for sale securities: Special Use Funds - Debt Securities [Member]
Marketable Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	96		96		58
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	24		24		7
Fair value of available for sale securities in an unrealized loss position	$ 220		$ 220		$ 240

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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