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Fair Value Measurements (Available for Sale Securities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Schedule of Available-for-sale Securities[Line Items]
Special Use Funds Storm Fund Assets	$ 68
Debt Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Realized gains	51
Realized losses	75
Proceeds from sale and maturity of Available-for-sale Securities	2,551
debt and equity securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Realized gains		$ 178	$ 116
Realized losses		83	76
Proceeds from sale and maturity of Available-for-sale Securities		2,817	3,400
Available for sale securities: Special Use Funds - Debt Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Unrealized gains	14	37
Unrealized losses	52	12
Fair Value	1,273	918
FPL[Member]
Schedule of Available-for-sale Securities[Line Items]
Special Use Funds Storm Fund Assets		0
FPL[Member] \| Debt Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Realized gains	31
Realized losses	49
Proceeds from sale and maturity of Available-for-sale Securities	2,100
FPL[Member] \| debt and equity securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Realized gains		75	53
Realized losses		50	44
Proceeds from sale and maturity of Available-for-sale Securities		1,902	$ 2,442
FPL[Member] \| Available for sale securities: Special Use Funds - Debt Securities [Member]
Schedule of Available-for-sale Securities[Line Items]
Unrealized gains	11	28
Unrealized losses	41	9
Fair Value	$ 961	$ 670
Accounting Standards Update 2016-01 [Member]
Schedule of Available-for-sale Securities[Line Items]
Reclassification of unrealized gains on investments				$ 312
Debt Securities [Member] \| FPL[Member] \| Storm Fund [Member]
Schedule of Available-for-sale Securities[Line Items]
Debt Securities, Available-for-sale, Term	1 year