Fair Value Measurements (Reconciliation of Changes in the Fair Value) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Realized and unrealized gains (losses): [Abstract]
Fair value based on significant unobservable inputs, ending balance	$ 528	$ 780	$ 528	$ 780
FPL [Member]
Realized and unrealized gains (losses): [Abstract]
Fair value based on significant unobservable inputs, ending balance	(2)	(1)	(2)	(1)
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	650	724	566	578
Realized and unrealized gains (losses): [Abstract]
Included in earnings	(131)	158	(79)	518
Included in other comprehensive income	1	(5)	5	(16)
Included in regulatory assets and liabilities	(1)	0	(1)	(2)
Purchases	22	38	125	83
Settlements	6	(77)	(1)	(234)
Issuances	(19)	(59)	(80)	(162)
Impact of adoption of new revenue standard			(30)	0
Transfers in			1	14
Transfers out	0	1	22	1
Fair value based on significant unobservable inputs, ending balance	528	780	528	780
Gains (losses) included in earnings attributable to the change in unrealized gains (losses) relating to derivatives held at the reporting date	(115)	213	(68)	461
Realized and unrealized gains (losses) reflected in operating revenues	(134)	164	(63)	519
Unrealized gains (losses) reflected in operating revenues related to derivatives still held at the reporting date	(118)	219	(53)	462
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	0	(2)	0	1
Realized and unrealized gains (losses): [Abstract]
Included in earnings	0	0	0	0
Included in other comprehensive income	0	0	0	0
Included in regulatory assets and liabilities	(1)	0	(1)	(2)
Purchases	0	0	0	0
Settlements	(1)	1	(2)	0
Issuances	0	0	0	0
Impact of adoption of new revenue standard			0	0
Transfers in			1	0
Transfers out	0	0	0	0
Fair value based on significant unobservable inputs, ending balance	(2)	(1)	(2)	(1)
Gains (losses) included in earnings attributable to the change in unrealized gains (losses) relating to derivatives held at the reporting date	0	$ 0	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	$ 142		$ 142