Fair Value Measurements (Reconciliation of Changes in the Fair Value) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Realized and unrealized gains (losses): [Abstract]
Fair value based on significant unobservable inputs, ending balance	$ 844	$ 627
FPL [Member]
Realized and unrealized gains (losses): [Abstract]
Fair value based on significant unobservable inputs, ending balance	(16)	(2)
Derivative Financial Instruments, Net [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value based on significant unobservable inputs, beginning balance	647	566
Realized and unrealized gains (losses): [Abstract]
Included in earnings	180	16
Included in other comprehensive income	3	(3)
Included in regulatory assets and liabilities	(2)	(1)
Purchases	24	42
Settlements	(39)	48
Issuances	(14)	(33)
Impact of adoption of new revenue standard	0	(30)
Transfers out	45	22
Gains (losses) included in earnings attributable to the change in unrealized gains (losses) relating to derivatives held at the reporting date	116	19
Realized and unrealized gains (losses) reflected in operating revenues	194	26
Unrealized gains (losses) reflected in operating revenues related to derivatives still held at the reporting date	130	29
Derivative Financial Instruments, Net [Member] | FPL [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value based on significant unobservable inputs, beginning balance	(36)	0
Realized and unrealized gains (losses): [Abstract]
Included in earnings	0	0
Included in other comprehensive income	0	0
Included in regulatory assets and liabilities	(2)	(2)
Purchases	0	0
Settlements	20	0
Issuances	0	0
Impact of adoption of new revenue standard	0	0
Transfers out	2	0
Gains (losses) included in earnings attributable to the change in unrealized gains (losses) relating to derivatives held at the reporting date	0	$ 0
Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member] | NextEra Energy Resources [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 147