Derivative Instruments, Net notional volumes and additional disclosures (Details) (USD $)	Jun. 30, 2011
Derivative, credit risk related contingent features [Abstract]
Fair value of derivative instruments with credit-risk-related contingent features that were in a liability position	$ 1,400,000,000
Total required posted collateral should FPL's and Capital Holdings' credit ratings fall to BBB/Baa2	200,000,000
Total required posted collateral should FPL's and Capital Holdings' credit ratings fall to below investment grade	2,300,000,000
Additional collateral requirements if non-ratings based contract provisions are triggered	650,000,000
Letters of credit posted through the normal course of business that could be applied toward the collateral requirements related to derivative instruments with credit-risk-related contingent features	90,000,000
Commodity contract - Power [Member]
Derivative [Line Items]
Non-monetary net notional volumes	(101)	[1]
Commodity contract - Natural gas [Member]
Derivative [Line Items]
Non-monetary net notional volumes	1,176	[2]
Commodity contract - Oil [Member]
Derivative [Line Items]
Non-monetary net notional volumes	(1)
Interest rate swaps [Member]
Derivative [Line Items]
Number of instruments held	25
Notional amount	5,600,000,000
Foreign currency swaps [Member]
Derivative [Line Items]
Number of instruments held	2
Notional amount	$ 544,000,000

[1] Megawatt-hours

[2] One million British thermal units