Fair Value Measurements (Assets and Liabilities Measured on a Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring [Line Items]
Special Use Funds Storm Fund Assets	$ 70	$ 68
Derivatives:
Derivative assets	2,229	1,919
Derivatives:
Derivative liability	1,472	1,191
Restricted cash	427	4,615
Fair value measurements made on a recurring basis [Member]
Cash equivalents:
Equity securities	924	486
Special use funds:
Equity securities	3,634	3,046
U.S. Government and municipal bonds	696	604
Corporate debt securities	777	728
Mortgage-backed securities	452	478
Other debt securities	116	146
Other investments:
Equity Securities	30	24
Debt securities	172	126
Fair value measurements made on a recurring basis [Member] | Commodity Contract [Member]
Derivatives:
Derivative asset, netting	(2,213)	(2,811)
Derivative assets	2,203	1,840
Derivatives:
Derivative liability, netting	(2,156)	(2,622)
Derivative liability	495	683
Fair value measurements made on a recurring basis [Member] | Interest Rate Contract [Member]
Derivatives:
Derivative asset, netting	(21)	(7)
Derivative assets	6	49
Derivatives:
Derivative liability, netting	(21)	(7)
Derivative liability	935	465
Fair value measurements made on a recurring basis [Member] | Foreign Currency Swap [Member]
Derivatives:
Derivative asset, netting	0	13
Derivative assets	20	30
Derivatives:
Derivative liability, netting	0	13
Derivative liability	42	43
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Cash equivalents:
Equity securities	924	486
Special use funds:
Equity securities	1,725	1,445
U.S. Government and municipal bonds	552	449
Corporate debt securities	0	0
Mortgage-backed securities	0	0
Other debt securities	0	0
Other investments:
Equity Securities	18	13
Debt securities	105	36
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member] | Commodity Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	1,003	1,379
Derivatives:
Derivative Liability, Gross Liability	1,030	1,329
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member] | Interest Rate Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	0	0
Derivatives:
Derivative Liability, Gross Liability	0	0
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member] | Foreign Currency Swap [Member]
Derivatives:
Derivative Asset, Gross Asset	0	0
Derivatives:
Derivative Liability, Gross Liability	0	0
Significant Other Observable Inputs (Level 2) [Member] | Fair value measurements made on a recurring basis [Member]
Cash equivalents:
Equity securities	0	0
Special use funds:
Equity securities	1,909	1,601
U.S. Government and municipal bonds	144	155
Corporate debt securities	777	728
Mortgage-backed securities	452	478
Other debt securities	116	145
Other investments:
Equity Securities	12	11
Debt securities	67	90
Significant Other Observable Inputs (Level 2) [Member] | Fair value measurements made on a recurring basis [Member] | Commodity Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	1,827	1,923
Derivatives:
Derivative Liability, Gross Liability	1,232	1,410
Significant Other Observable Inputs (Level 2) [Member] | Fair value measurements made on a recurring basis [Member] | Interest Rate Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	27	56
Derivatives:
Derivative Liability, Gross Liability	810	336
Significant Other Observable Inputs (Level 2) [Member] | Fair value measurements made on a recurring basis [Member] | Foreign Currency Swap [Member]
Derivatives:
Derivative Asset, Gross Asset	20	17
Derivatives:
Derivative Liability, Gross Liability	42	30
Significant Unobservable Inputs (Level 3) [Member] | Fair value measurements made on a recurring basis [Member]
Cash equivalents:
Equity securities	0	0
Special use funds:
Equity securities	0	0
U.S. Government and municipal bonds	0	0
Corporate debt securities	0	0
Mortgage-backed securities	0	0
Other debt securities	0	1
Other investments:
Equity Securities	0	0
Debt securities	0	0
Significant Unobservable Inputs (Level 3) [Member] | Fair value measurements made on a recurring basis [Member] | Commodity Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	1,586	1,349
Derivatives:
Derivative Liability, Gross Liability	389	566
Significant Unobservable Inputs (Level 3) [Member] | Fair value measurements made on a recurring basis [Member] | Interest Rate Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	0	0
Derivatives:
Derivative Liability, Gross Liability	146	136
Significant Unobservable Inputs (Level 3) [Member] | Fair value measurements made on a recurring basis [Member] | Foreign Currency Swap [Member]
Derivatives:
Derivative Asset, Gross Asset	0	0
Derivatives:
Derivative Liability, Gross Liability	0	0
Other Current Assets [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives:
Restricted cash	66	85
Other Noncurrent Assets [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives:
Restricted cash	89
FPL [Member]
Fair Value, Assets and Liabilities Measured on Recurring [Line Items]
Special Use Funds Storm Fund Assets	70	68
Derivatives:
Derivative assets	7	0
Derivatives:
Derivative liability	16	41
Restricted cash	151	142
FPL [Member] | Fair value measurements made on a recurring basis [Member]
Cash equivalents:
Equity securities	196	206
Special use funds:
Equity securities	2,284	1,850
U.S. Government and municipal bonds	525	470
Corporate debt securities	542	544
Mortgage-backed securities	344	367
Other debt securities	106	132
FPL [Member] | Fair value measurements made on a recurring basis [Member] | Commodity Contract [Member]
Derivatives:
Derivative asset, netting	(3)	(2)
Derivative assets	7	0
Derivatives:
Derivative liability, netting	(3)	(2)
Derivative liability	16	41
FPL [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Cash equivalents:
Equity securities	196	206
Special use funds:
Equity securities	553	398
U.S. Government and municipal bonds	420	350
Corporate debt securities	0	0
Mortgage-backed securities	0	0
Other debt securities	0	0
FPL [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member] | Commodity Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	0	0
Derivatives:
Derivative Liability, Gross Liability	0	0
FPL [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value measurements made on a recurring basis [Member]
Cash equivalents:
Equity securities	0	0
Special use funds:
Equity securities	1,731	1,452
U.S. Government and municipal bonds	105	120
Corporate debt securities	542	544
Mortgage-backed securities	344	367
Other debt securities	106	131
FPL [Member] | Significant Other Observable Inputs (Level 2) [Member] | Fair value measurements made on a recurring basis [Member] | Commodity Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	9	2
Derivatives:
Derivative Liability, Gross Liability	8	7
FPL [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value measurements made on a recurring basis [Member]
Cash equivalents:
Equity securities	0	0
Special use funds:
Equity securities	0	0
U.S. Government and municipal bonds	0	0
Corporate debt securities	0	0
Mortgage-backed securities	0	0
Other debt securities	0	1
FPL [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair value measurements made on a recurring basis [Member] | Commodity Contract [Member]
Derivatives:
Derivative Asset, Gross Asset	1	0
Derivatives:
Derivative Liability, Gross Liability	11	36
FPL [Member] | Other Current Assets [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives:
Restricted cash	62	$ 81
FPL [Member] | Other Noncurrent Assets [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives:
Restricted cash	$ 89