Commitments and Contingencies (Long-term Purchase Commitment) (Details) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2018 USD ($) MW	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) MW	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
FPL [Member]
Required capacity and/or minimum payments [Abstract]
Capacity payments		$ 6	$ 18	$ 16	$ 58
Energy payments		8	$ 28	$ 23	$ 70
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 2018		5		$ 5
2019		15		15
2020		15		15
2021		15		15
2022		20		20
Thereafter		195		195
FPL [Member] | Natural Gas, Including Transportation And Storage, Contract Minimum Payments [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2018		495		495
2019		1,420		1,420
2020		1,055		1,055
2021		940		940
2022		925		925
Thereafter		11,660		11,660
FPL [Member] | Coal Contract Minimum Payments [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2018		15		15
2019		5		5
2020		0		0
2021		0		0
2022		0		0
Thereafter		0		0
FPL [Member] | Take-or-Pay Contract Range 1 [Member]
Required capacity and/or minimum payments [Abstract]
Minimum annual purchase commitments (in megawatts) | MW	375
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 2018		80		80
2019		320		320
2020		385		385
2021		415		415
2022		415		415
Thereafter		7,585		7,585
NextEra Energy Resources [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2018		1,110		1,110
2019		1,760		1,760
2020		195		195
2021		160		160
2022		180		180
Thereafter		1,470		1,470
NextEra Energy Resources [Member] | Contract Group 1 [Member]
Long-term Purchase Commitment [Line Items]
Commitment amount included in capital expenditures		3,200		3,200
NextEra Energy Resources [Member] | Mountain Valley Pipeline [Member]
Required capacity and/or minimum payments [Abstract]
2019		15		15
2020		65		65
2021		65		65
2022		65		65
Thereafter		$ 1,085		$ 1,085
Equity method investment, ownership percentage		31.00%		31.00%
Corporate and Other [Member]
Required capacity and/or minimum payments [Abstract]
Remainder of 2018		$ 155		$ 155
2019		25		25
2020		10		10
2021		10		10
2022		5		5
Thereafter		0		0
Commitment to invest		60		60
Joint Obligations Remainder Current Year		200		200
Joint Obligations Second Year		$ 250		$ 250
Jointly Owned Electricity Generation Plant [Member] | FPL [Member]
Required capacity and/or minimum payments [Abstract]
Public utilities, termination of operations, payment	$ 90
Proportionate ownership percentage	20.00%
Regulatory asset	$ 150
Plant in service, net book value	$ 191
Regulatory asset amortization period (in years)	15 years
Regulatory liabilities						$ 62
Jointly Owned Electricity Generation Plant [Member] | JEA [Member]
Required capacity and/or minimum payments [Abstract]
Proportionate ownership percentage	80.00%
Jointly Owned Electricity Generation Plant [Member] | Take-or-Pay Purchased Power Contract [Member] | FPL [Member]
Required capacity and/or minimum payments [Abstract]
Regulatory asset						$ 90
Jointly Owned Electricity Generation Plant [Member] | Environmental Cost Recovery [Member] | FPL [Member]
Required capacity and/or minimum payments [Abstract]
Regulatory asset amortization period (in years)	10 years