Fair Value Measurements (Reconciliation of Change in Fair Value of Derivatives, Significant Unobservable Inputs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Realized and unrealized gains (losses):
Realized and unrealized gains (losses) reflected in operating revenues	$ 220		$ 441		$ 384
Unrealized gains (losses) reflected in operating revenues, for derivatives still held at the reporting date	157		423		153
Purchases	273		270
Settlements	181		166
Issuances	243		362
Derivative Financial Instruments, Net [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of derivatives based on significant unobservable inputs beginning balance	486		296		364
Realized and unrealized gains (losses):
Realized and unrealized gains (losses) included in earnings	218	[1]	454	[1]	407	[1]
Realized and unrealized gains (losses) included in regulatory assets and liabilities	5		3		1
Purchases, sales, settlements and issuances	(151)	[2]	(258)	[2]	(432)	[2]
Transfers in	20	[3]	6	[3]	2	[3]
Transfers out	(12)	[3]	(15)	[3]	(46)	[3]
Fair value of derivatives based on significant unobservable inputs ending balance	566		486		296
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	152	[4]	423	[4]	170	[4]
FPL [Member] | Derivative Financial Instruments, Net [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of derivatives based on significant unobservable inputs beginning balance	4		7		11
Realized and unrealized gains (losses):
Realized and unrealized gains (losses) included in earnings	0		0		0
Realized and unrealized gains (losses) included in regulatory assets and liabilities	5		3		1
Purchases, sales, settlements and issuances	(7)		(6)		(5)
Transfers in	0		0		0
Transfers out	0		0		0
Fair value of derivatives based on significant unobservable inputs ending balance	2		4		7
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

[1] For the years ended December 31, 2012, 2011 and 2010, $220 million, $441 million and $384 million, respectively, of realized and unrealized gains are reflected in the consolidated statements of income in operating revenues and the balance is reflected in fuel, purchased power and interchange.

[2] For the years ended December 31, 2012 and 2011, includes $273 million and $270 million of purchases, $181 million and $166 million of settlements and $243 million and $362 million of issuances, respectively.

[3] Transfers into Level 3 were a result of decreased observability of market data and transfers from Level 3 to Level 2 were a result of increased observability of market data. NEE's and FPL's policy is to recognize all transfers at the beginning of the reporting period.

[4] For the years ended December 31, 2012, 2011 and 2010, $157 million, $423 million and $153 million, respectively, of unrealized gains are reflected in the consolidated statements of income in operating revenues and the balance is reflected in fuel, purchased power and interchange.