Derivative Instruments (Balance Sheet Disclosure) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	$ 1,971	$ 1,999
Derivative Liabilities	1,428	1,755
Current derivative assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	712	990
Margin cash collateral received from counterparties	279	197
Long Lived Assets Held-for-sale, Name [Domain]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	57
Non Current Derivative Assets Member [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	1,202	1,009
Margin cash collateral received from counterparties	151	97
Current derivative liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Liabilities	882	1,289
Margin cash collateral paid to counterparties	46	20
liabilities associated with assets held-for-sale [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Liabilities	16
Noncurrent derivative liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Liabilities	530	466
Margin cash collateral paid to counterparties	13	10
Commodity contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	1,937	1,949
Derivative Liabilities	982	1,358
Interest Rate Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	34	50
Derivative Liabilities	319	266
Foreign currency swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	0	0
Derivative Liabilities	127	131
Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	33	35
Derivative Liability, Fair Value, Gross Liability	287	257
Designated as Hedging Instrument [Member] \| Commodity contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	33	35
Derivative Liability, Fair Value, Gross Liability	155	126
Designated as Hedging Instrument [Member] \| Foreign currency swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	132	131
Not Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	5,908	6,145
Derivative Liability, Fair Value, Gross Liability	4,740	5,415
Not Designated as Hedging Instrument [Member] \| Commodity contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	5,906	6,145
Derivative Liability, Fair Value, Gross Liability	4,580	5,290
Not Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	2	0
Derivative Liability, Fair Value, Gross Liability	160	125
Not Designated as Hedging Instrument [Member] \| Foreign currency swap [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
FPL [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	4	7
Derivative Liabilities	222	370
FPL [Member] \| Current derivative liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Liabilities	222	370
FPL [Member] \| Current other assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	3	6
FPL [Member] \| Other Noncurrent Assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	1	1
FPL [Member] \| Commodity contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	4	7
Derivative Liabilities	222	370
FPL [Member] \| Designated as Hedging Instrument [Member] \| Commodity contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
FPL [Member] \| Not Designated as Hedging Instrument [Member] \| Commodity contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	7	8
Derivative Liability, Fair Value, Gross Liability	$ 225	$ 371

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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