Fair Value Measurements (Nonrecurring Fair Value Measurements) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011 mW	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment charges	$ 0	$ 51,000,000	$ 19,000,000
Expiration Date of Agreements for Continuing Involvement - Minimum	2013
Expiration Date of Agreements for Continuing Involvement - Maximum	2016
Natural gas fired generating facilities capacity, (in megawatts)		2,700
Loss on sale of natural gas-fired generating assets	0	151,000,000	0
Loss on sale of natural gas-fired generating assets, after-tax		98,000,000
NextEra Energy Resources [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net cash proceeds from sale of ownership interest		1,200,000,000
Repayments of long-term debt, related to assets sold		363,000,000
Loss on sale of natural gas-fired generating assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss reclassified from AOCI to earnings		30,000,000
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of property, plant, and equipment prior to impairment charge		79,000,000
Property, plant, and equipment, fair value disclosure		28,000,000
Impairment charges		51,000,000
Impairment charges, after-tax		$ 31,000,000