Fair Value Measurements (Reconciliation of Changes in the Fair Value) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Realized and unrealized gains (losses): [Abstract]
Realized and unrealized gains (losses) reflected in operating revenues	$ 131	$ 42	$ 379	$ (410)
Fair Value Net Assets Liabilities Measured On Recurring Basis Gain Loss Included In Interest Expense			(11)	(61)
Unrealized gains (losses) reflected in operating revenues related to derivatives still held at the reporting date	123	(43)	271	(107)
Financial Instruments, Net [Member]
Reconciliation of changes in fair value based on significant unobservable inputs Roll Forward [Abstract]
Fair value based on significant unobservable inputs, beginning balance	544	354	622	622
Realized and unrealized gains (losses): [Abstract]
Included in Earnings	115	22	369	(474)
Included in other comprehensive income	0	11	8	11
Included in regulatory assets and liabilities	(1)	1	3	6
Purchases	42	209	125	223
Settlements	(109)	(36)	(376)	268
Issuances	(32)	(9)	(164)	(103)
Transfers in	3	0	(15)	16
Transfers out	(16)	(136)	(26)	(153)
Fair value based on significant unobservable inputs, ending balance	546	416	546	416
The amount of gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to derivatives still held at the reporting date	107	(63)	260	(168)
FPL [Member] | Financial Instruments, Net [Member]
Reconciliation of changes in fair value based on significant unobservable inputs Roll Forward [Abstract]
Fair value based on significant unobservable inputs, beginning balance	4	3	5	0
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)	1	3	6
Purchases	0	197	0	197
Settlements	(1)	0	(6)	(2)
Issuances	0	0	0	0
Transfers in	0	0	0	0
Transfers out	0	0	0	0
Fair value based on significant unobservable inputs, ending balance	2	201	2	201
The amount of gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to derivatives still held at the reporting date	$ 0	$ 0	$ 0	$ 0