Commitments and Contingencies (Long-term Purchase Commitment) (Details) $ in Millions	1 Months Ended			3 Months Ended		9 Months Ended
	Jul. 31, 2018	Jan. 31, 2018 USD ($)	Jan. 31, 2017 USD ($) MW	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) MW	Sep. 30, 2016 USD ($)
FPL [Member]
Required capacity and/or minimum payments [Abstract]
Capacity payments				$ 18	$ 41	$ 58	$ 134
Energy payments				28	$ 57	$ 70	$ 103
FPL [Member] | Take-or-Pay Contract Range 1 [Member]
Long-term Purchase Commitment [Line Items]
Minimum annual purchase commitments (in megawatts) | MW						375
FPL [Member] | Pay-for-Performance Contracts [Member]
Long-term Purchase Commitment [Line Items]
Minimum total purchase commitments (in megawatts) | MW						114
FPL [Member] | Capacity Charges [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2017				20		$ 20
2018				65		65
2019				50		50
2020				20		20
2021				20		20
Thereafter				250		250
FPL [Member] | Natural Gas, Including Transportation And Storage, Contract Minimum Payments [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2017				480		480
2018				1,305		1,305
2019				865		865
2020				910		910
2021				905		905
Thereafter				12,135		12,135
FPL [Member] | Coal Contract Minimum Payments [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2017				35		35
2018				35		35
2019				5		5
2020				0		0
2021				0		0
Thereafter				0		0
FPL [Member] | Sabal Trail and Florida Southeast Connection [Member] | Natural Gas, Including Transportation And Storage, Contract Minimum Payments [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2017				75		75
2018				295		295
2019				290		290
2020				360		360
2021				390		390
Thereafter				7,565		7,565
NextEra Energy Resources [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2017				570		570
2018				1,455		1,455
2019				135		135
2020				105		105
2021				80		80
Thereafter				390		390
NextEra Energy Resources [Member] | Contract Group 1 [Member]
Long-term Purchase Commitment [Line Items]
Commitment amount included in capital expenditures				2,500		2,500
Indiantown, Florida [Member] | FPL [Member] | Coal Fired Generation Facility [Member]
Long-term Purchase Commitment [Line Items]
Coal fired generating facility capacity (in megawatts) | MW			330
Purchase price			$ 451
Existing debt assumed			218
Other Regulatory Assets (Liabilities) [Member] | Indiantown, Florida [Member] | FPL [Member] | Coal Fired Generation Facility [Member]
Long-term Purchase Commitment [Line Items]
Regulatory asset			$ 451
Regulatory asset amortization period (in years)			9 years
Corporate and Other [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2017				55		55
2018				45		45
2019				15		15
2020				15		15
2021				10		10
Thereafter				0		0
Commitment to invest				90		90
Joint Obligations Of NEECH and NEER included NEER Amounts due in the current year				170		170
Jointly Owned Electricity Generation Plant [Member] | FPL [Member]
Long-term Purchase Commitment [Line Items]
Plant in service, net book value				$ 193		$ 193
Scenario, Forecast [Member] | Jointly Owned Electricity Generation Plant [Member] | FPL [Member]
Long-term Purchase Commitment [Line Items]
Proportionate ownership percentage		20.00%
Regulatory asset		$ 150
Regulatory asset amortization period (in years)	15 years
Termination of operations, future payment		$ 90
Scenario, Forecast [Member] | Jointly Owned Electricity Generation Plant [Member] | JEA [Member]
Long-term Purchase Commitment [Line Items]
Proportionate ownership percentage		80.00%
Scenario, Forecast [Member] | Jointly Owned Electricity Generation Plant [Member] | Environmental Cost Recovery [Member] | FPL [Member]
Long-term Purchase Commitment [Line Items]
Regulatory asset amortization period (in years)	10 years