Fair Value Measurements (Fair Value of Instruments Recorded at Other Than Fair Value and Special Use Funds) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Special use funds: nuclear decommissioning fund assets	$ 6,564		$ 6,564		$ 5,818
Special Use Funds Storm Fund Assets	70		70		68
Available for sale debt securities amortized cost	1,962		$ 1,962		1,994
Special Use Funds Nuclear Decommissioning Funds Weighted Average Maturity			8 years
Fair Value Assumptions, Expected Term			1 year
Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Special Use Funds Fair Value Disclosure	958		$ 958		884
Other Investments Financial Instruments Primarily Notes Receivable Fair Value Disclosure	30		30		54
Long Term Debt Including Current Maturities Fair Value Disclosure	39,032		39,032		29,498
Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Special Use Funds Fair Value Disclosure	957		957		883
Other Investments Financial Instruments Primarily Notes Receivable Fair Value Disclosure	30		30		54
Long Term Debt Including Current Maturities Fair Value Disclosure	42,362		42,362		30,043
FPL [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Special use funds: nuclear decommissioning fund assets	4,499		4,499		3,987
Special Use Funds Storm Fund Assets	70		70		68
Available for sale debt securities amortized cost	1,457		$ 1,457		1,542
Special Use Funds Nuclear Decommissioning Funds Weighted Average Maturity			8 years
Fair Value Assumptions, Expected Term			1 year
FPL [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Special Use Funds Fair Value Disclosure	767		$ 767		693
Long Term Debt Including Current Maturities Fair Value Disclosure	14,171		14,171		11,783
FPL [Member] | Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Special Use Funds Fair Value Disclosure	766		766		692
Long Term Debt Including Current Maturities Fair Value Disclosure	16,567		16,567		$ 12,613
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
marketable securities, unrealized gain (loss) recognized during the period on securities still held	21	$ 192	500	$ 226
Equity Securities [Member] | FPL [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
marketable securities, unrealized gain (loss) recognized during the period on securities still held	$ 18	$ 130	$ 327	$ 167