Commitments and Contingencies (Required Capacity and/or Minimum Payments Under Contracts) (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) MW	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Corporate and Other [Member]
Long-term Purchase Commitment [Line Items]
Capacity payments and/or minimum payments - 2018		$ 80
Capacity payments and/or minimum payments - 2019		15
Capacity payments and/or minimum payments - 2020		15
Capacity payments and/or minimum payments - 2021		10
Capacity payments and/or minimum payments - 2022		0
Capacity payments and/or minimum payments - Thereafter		0
Commitment to invest		75
Joint obligations due in the next year		60
FPL[Member]
Long-term Purchase Commitment [Line Items]
Capacity payments		72	$ 175	$ 434
Energy payments		$ 90	$ 126	$ 262
FPL[Member] | Take-or-Pay Purchased Power Contract [Member]
Long-term Purchase Commitment [Line Items]
Minimum purchase commitments (in megawatts) | MW		375
FPL[Member] | Pay-for-Performance Contracts [Member]
Long-term Purchase Commitment [Line Items]
Minimum purchase commitments (in megawatts) | MW		114
FPL[Member] | Capacity Charges [Member]
Long-term Purchase Commitment [Line Items]
Capacity payments and/or minimum payments - 2018		$ 20
Capacity payments and/or minimum payments - 2019		20
Capacity payments and/or minimum payments - 2020		20
Capacity payments and/or minimum payments - 2021		20
Capacity payments and/or minimum payments - 2022		20
Capacity payments and/or minimum payments - Thereafter		225
FPL[Member] | Natural Gas Including Transportation and Storage Contract Minimum Payments [Member]
Long-term Purchase Commitment [Line Items]
Capacity payments and/or minimum payments - 2018		1,310
Capacity payments and/or minimum payments - 2019		865
Capacity payments and/or minimum payments - 2020		910
Capacity payments and/or minimum payments - 2021		905
Capacity payments and/or minimum payments - 2022		895
Capacity payments and/or minimum payments - Thereafter		11,240
FPL[Member] | Natural Gas Including Transportation and Storage Contract Minimum Payments [Member] | Sabal Trail and Florida Southeast Connection [Member]
Long-term Purchase Commitment [Line Items]
Capacity payments and/or minimum payments - 2018		295
Capacity payments and/or minimum payments - 2019		290
Capacity payments and/or minimum payments - 2020		360
Capacity payments and/or minimum payments - 2021		390
Capacity payments and/or minimum payments - 2022		390
Capacity payments and/or minimum payments - Thereafter		7,175
FPL[Member] | Coal Including Transportation Contract Minimum Payments [Member]
Long-term Purchase Commitment [Line Items]
Capacity payments and/or minimum payments - 2018		35
Capacity payments and/or minimum payments - 2019		5
Capacity payments and/or minimum payments - 2020		0
Capacity payments and/or minimum payments - 2021		0
Capacity payments and/or minimum payments - 2022		0
Capacity payments and/or minimum payments - Thereafter		0
NEER [Member]
Long-term Purchase Commitment [Line Items]
Capacity payments and/or minimum payments - 2018		1,700
Capacity payments and/or minimum payments - 2019		205
Capacity payments and/or minimum payments - 2020		120
Capacity payments and/or minimum payments - 2021		80
Capacity payments and/or minimum payments - 2022		100
Capacity payments and/or minimum payments - Thereafter		290
NEER [Member] | Contract Group 1 [Member]
Long-term Purchase Commitment [Line Items]
Commitment amount included in capital expenditures		2,200
Jointly Owned Electricity Generation Plant [Member] | FPL[Member]
Long-term Purchase Commitment [Line Items]
Plant in service, net book value		191
Regulatory liabilities		62
Jointly Owned Electricity Generation Plant [Member] | FPL[Member] | Forecast [Member]
Long-term Purchase Commitment [Line Items]
Regulatory Assets	$ 150
Regulatory Asset, Amortization Period	15 years
Jointly Owned Electricity Generation Plant [Member] | Subsequent Event [Member] | FPL[Member]
Long-term Purchase Commitment [Line Items]
Termination of operations, future payment	$ 90
Proportionate ownership share	20.00%
Jointly Owned Electricity Generation Plant [Member] | Subsequent Event [Member] | JEA [Member]
Long-term Purchase Commitment [Line Items]
Proportionate ownership share	80.00%
Take-or-Pay Purchased Power Contract [Member] | Jointly Owned Electricity Generation Plant [Member] | FPL[Member]
Long-term Purchase Commitment [Line Items]
Regulatory Assets		$ 90
Environmental Restoration Costs [Member] | Jointly Owned Electricity Generation Plant [Member] | FPL[Member] | Forecast [Member]
Long-term Purchase Commitment [Line Items]
Regulatory Asset, Amortization Period	10 years