Income Taxes - Reconciliation Between the Effective Income Tax Rates and the Applicable Statutory Rate (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Effective Income Tax Rate Reconciliation [Line Items]
Statutory federal income tax rate	21.00%	21.00%	21.00%	21.00%
Increases (reductions) resulting from:
State income taxes - net of federal income tax benefit(b)	4.30%	1.80%	3.40%	4.30%
Taxes attributable to noncontrolling interests	2.00%	1.20%	1.90%	2.20%
PTCs and ITCs - NEER	(11.50%)	(5.20%)	(7.90%)	(2.40%)
Amortization of deferred regulatory credit	(5.60%)	(4.10%)	(7.00%)	(1.50%)
Other - net	(3.40%)	(3.00%)	(2.30%)	(0.90%)
Effective income tax rate	6.80%	11.70%	9.10%	22.70%
Tax Cuts and Jobs Act of 2017, income tax expense (benefit)				$ 125
State [Member]
Increases (reductions) resulting from:
Deferred state tax credits	$ 48		$ 48
FPL [Member]
Effective Income Tax Rate Reconciliation [Line Items]
Statutory federal income tax rate	21.00%	21.00%	21.00%	21.00%
Increases (reductions) resulting from:
State income taxes - net of federal income tax benefit(b)	3.90%	4.70%	3.30%	4.40%
Taxes attributable to noncontrolling interests	0.00%	0.00%	0.00%	0.00%
PTCs and ITCs - NEER	0.00%	0.00%	0.00%	0.00%
Amortization of deferred regulatory credit	(5.20%)	(5.40%)	(8.00%)	(4.60%)
Other - net	(1.60%)	(1.40%)	(0.70%)	(0.80%)
Effective income tax rate	18.10%	18.90%	15.60%	20.00%
Income tax benefits related to the amortization of deferred regulatory credits			$ 83
Amortization of excess deferred income taxes			$ 870
Amortization period			10 years

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