Derivative Instruments (Balance Sheet Disclosure) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	$ 1,804	$ 2,235
Derivative Liabilities	899	881
Current derivative assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	489	885
Margin cash collateral received from counterparties	39	96
Non Current Derivative Assets Member [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	1,315	1,350
Margin cash collateral received from counterparties		71
Current derivative liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Liabilities	364	404
Noncurrent derivative liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Liabilities	535	477
Margin cash collateral paid to counterparties	39
Not Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	4,012	4,879
Derivative Liability, Fair Value, Gross Liability	3,107	3,358
Derivative Assets	1,804	2,235
Derivative Liabilities	899	881
Not Designated as Hedging Instrument [Member] \| Commodity contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	3,962	4,590
Derivative Liability, Fair Value, Gross Liability	2,792	2,968
Derivative Assets	1,737	1,938
Derivative Liabilities	567	483
Not Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	50	288
Derivative Liability, Fair Value, Gross Liability	275	284
Derivative Assets	55	296
Derivative Liabilities	280	292
Not Designated as Hedging Instrument [Member] \| Foreign currency contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	0	1
Derivative Liability, Fair Value, Gross Liability	40	106
Derivative Assets	12	1
Derivative Liabilities	52	106
FPL[Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	2	209
Derivative Liabilities	2	1
FPL[Member] \| Current derivative assets [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Assets	2	209
FPL[Member] \| Other Current Liabilities [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Liabilities	2	1
FPL[Member] \| Not Designated as Hedging Instrument [Member] \| Commodity contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Abstract]
Derivative Asset, Fair Value, Gross Asset	3	212
Derivative Liability, Fair Value, Gross Liability	3	4
Derivative Assets	2	209
Derivative Liabilities	$ 2	$ 1

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Fair value, after effects of master netting arrangements, of 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 offset against an obligation to return collateral. Includes assets not subject to a master netting arrangement and not elected to be offset.

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