Non-Derivative Fair Value Measurements (Assets and Liabilities Measured on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets [Abstract]
Restricted cash	$ 441	$ 508
Derivatives [Abstract]
Derivative Assets	2,217	2,386
Derivatives [Abstract]
Derivative Liabilities	1,510	1,340
Fair Value, Recurring [Member]
Assets [Abstract]
Cash equivalents and restricted cash - equity securities	742	363
Special use funds [Abstract]
Equity securities	4,726	3,963
U.S. Government and municipal bonds	717	717
Corporate debt securities	871	748
Mortgage-backed securities	422	517
Other debt securities	124	117
Other Investments [Abstract]
Equity securities	62	46
Debt securities	218	151
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member]
Assets [Abstract]
Cash equivalents and restricted cash - equity securities	742	363
Special use funds [Abstract]
Equity securities	2,237	1,875
U.S. Government and municipal bonds	590	567
Corporate debt securities	1	0
Mortgage-backed securities	0	0
Other debt securities	0	0
Other Investments [Abstract]
Equity securities	62	34
Debt securities	91	82
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member] | Current other assets [Member]
Assets [Abstract]
Restricted cash	111	60
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member] | Other Noncurrent Assets [Member]
Assets [Abstract]
Restricted cash	42	64
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Assets [Abstract]
Cash equivalents and restricted cash - equity securities	0	0
Special use funds [Abstract]
Equity securities	2,489	2,088
U.S. Government and municipal bonds	127	150
Corporate debt securities	870	748
Mortgage-backed securities	422	517
Other debt securities	124	117
Other Investments [Abstract]
Equity securities	0	12
Debt securities	127	69
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Recurring [Member]
Assets [Abstract]
Cash equivalents and restricted cash - equity securities	0	0
Special use funds [Abstract]
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	0
Other Investments [Abstract]
Equity securities	0	0
Debt securities	0	0
Commodity contracts [Member] | Fair Value, Recurring [Member]
Derivatives [Abstract]
Asset offsetting	2,325	2,700
Derivative Assets	2,154	2,350
Derivatives [Abstract]
Liability offsetting	2,277	2,625
Derivative Liabilities	500	576
Commodity contracts [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	919	1,229
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	1,004	1,365
Commodity contracts [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	1,881	2,082
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	1,468	1,446
Commodity contracts [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	1,679	1,739
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	305	390
Interest Rate Contract [Member] | Fair Value, Recurring [Member]
Derivatives [Abstract]
Asset offsetting	41	17
Derivative Assets	40	9
Derivatives [Abstract]
Liability offsetting	41	17
Derivative Liabilities	1,001	725
Interest Rate Contract [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	0	0
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	0
Interest Rate Contract [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	81	24
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	1,042	598
Interest Rate Contract [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	0	2
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	144
Currency Swap [Member] | Fair Value, Recurring [Member]
Derivatives [Abstract]
Asset offsetting	34	(1)
Derivative Assets	23	27
Derivatives [Abstract]
Liability offsetting	34	(1)
Derivative Liabilities	9	39
Currency Swap [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	0	0
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	0
Currency Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	57	26
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	43	38
Currency Swap [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	0	0
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	0
FPL[Member]
Assets [Abstract]
Restricted cash	76	118
Derivatives [Abstract]
Derivative Liabilities	3	13
FPL[Member] | Fair Value, Recurring [Member]
Assets [Abstract]
Cash equivalents and restricted cash - equity securities	78	156
Special use funds [Abstract]
Equity securities	3,012	2,491
U.S. Government and municipal bonds	536	535
Corporate debt securities	627	533
Mortgage-backed securities	335	395
Other debt securities	119	111
FPL[Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member]
Assets [Abstract]
Cash equivalents and restricted cash - equity securities	78	156
Special use funds [Abstract]
Equity securities	752	596
U.S. Government and municipal bonds	449	429
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, Recurring [Member] | Current other assets [Member]
Assets [Abstract]
Restricted cash	56	54
FPL[Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member] | Other Noncurrent Assets [Member]
Assets [Abstract]
Restricted cash	17	64
FPL[Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Assets [Abstract]
Cash equivalents and restricted cash - equity securities	0	0
Special use funds [Abstract]
Equity securities	2,260	1,895
U.S. Government and municipal bonds	87	106
Corporate debt securities	627	533
Mortgage-backed securities	335	395
Other debt securities	119	111
FPL[Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Recurring [Member]
Assets [Abstract]
Cash equivalents and restricted cash - equity securities	0	0
Special use funds [Abstract]
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	0
FPL[Member] | Commodity contracts [Member] | Fair Value, Recurring [Member]
Derivatives [Abstract]
Asset offsetting	0	1
Derivative Assets	3	3
Derivatives [Abstract]
Liability offsetting	0	1
Derivative Liabilities	3	13
FPL[Member] | Commodity contracts [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	0	0
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	0
FPL[Member] | Commodity contracts [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	1	3
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	5
FPL[Member] | Commodity contracts [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Recurring [Member]
Other Investments [Abstract]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	2	1
Derivatives [Abstract]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ 3	$ 9