Fair Value Measurements (Significant Unobservable Inputs Used in Valuation of Contracts) (Details) - Level 3 [Member] $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares $ / MWh $ / MMBTU
Forward Contracts - Power [Member] | Discounted Cash Flow Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Forward price (in dollars per energy unit) | $ / MWh	0
Forward Contracts - Power [Member] | Discounted Cash Flow Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Forward price (in dollars per energy unit) | $ / MWh	109
Forward contracts - Gas [Member] | Discounted Cash Flow Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Forward price (in dollars per energy unit) | $ / MMBTU	1
Forward contracts - Gas [Member] | Discounted Cash Flow Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Forward price (in dollars per energy unit) | $ / MMBTU	5
Forward contracts - Other [Member] | Discounted Cash Flow Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Expected rates (in dollars per unit) | $ / shares	$ (6)
Forward contracts - Other [Member] | Discounted Cash Flow Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Expected rates (in dollars per unit) | $ / shares	$ 51
Option Contracts, Power [Member] | Option Models [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Implied volatilities (percent)	8.00%
Implied correlations (percent)	(5.00%)
Option Contracts, Power [Member] | Option Models [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Implied volatilities (percent)	320.00%
Implied correlations (percent)	99.00%
Option Contracts, Primarily Gas [Member] | Option Models [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Implied volatilities (percent)	1.00%
Implied correlations (percent)	(5.00%)
Option Contracts, Primarily Gas [Member] | Option Models [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Implied volatilities (percent)	94.00%
Implied correlations (percent)	99.00%
Full Requirements and Unit Contingent Contracts [Member] | Discounted Cash Flow Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Forward price (in dollars per energy unit) | $ / MWh	(25)
Customer migration rate (percent)	0.00%
Full Requirements and Unit Contingent Contracts [Member] | Discounted Cash Flow Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Forward price (in dollars per energy unit) | $ / MWh	318
Customer migration rate (percent)	20.00%
Interest Rate Swap [Member] | NextEra Energy Resources [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure	$ 118
Derivative Financial Instruments, Liabilities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure	613
Derivative Financial Instruments, Liabilities [Member] | Forward Contracts - Power [Member] | Discounted Cash Flow Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure	237
Derivative Financial Instruments, Liabilities [Member] | Forward contracts - Gas [Member] | Discounted Cash Flow Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure	12
Derivative Financial Instruments, Liabilities [Member] | Forward contracts - Other [Member] | Discounted Cash Flow Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure	1
Derivative Financial Instruments, Liabilities [Member] | Option Contracts, Power [Member] | Option Models [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure	38
Derivative Financial Instruments, Liabilities [Member] | Option Contracts, Primarily Gas [Member] | Option Models [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure	278
Derivative Financial Instruments, Liabilities [Member] | Full Requirements and Unit Contingent Contracts [Member] | Discounted Cash Flow Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liabilities, Fair Value Disclosure	47
Derivative Financial Instruments, Assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	1,263
Derivative Financial Instruments, Assets [Member] | Forward Contracts - Power [Member] | Discounted Cash Flow Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	644
Derivative Financial Instruments, Assets [Member] | Forward contracts - Gas [Member] | Discounted Cash Flow Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	33
Derivative Financial Instruments, Assets [Member] | Forward contracts - Other [Member] | Discounted Cash Flow Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	7
Derivative Financial Instruments, Assets [Member] | Option Contracts, Power [Member] | Option Models [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	57
Derivative Financial Instruments, Assets [Member] | Option Contracts, Primarily Gas [Member] | Option Models [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	230
Derivative Financial Instruments, Assets [Member] | Full Requirements and Unit Contingent Contracts [Member] | Discounted Cash Flow Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 292