Derivative Instruments (Balance Sheet Disclosure) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative assets	$ 2,143	$ 2,217
Derivative Asset, Current	771	570
Derivative Asset, Noncurrent	1,372	1,647
Derivative liability	2,388	1,510
Derivative Liability, Current	1,198	311
Derivative Liability, Noncurrent	1,190	1,199
Non Current Derivative Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral		184
Current Derivative Assets Member [Domain]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Offset Against Collateral	151
Current derivative liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	2	136
Non Current derivative liabilities [Domain]
Derivatives, Fair Value [Line Items]
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	119
Commodity Contract [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	2,062	2,154
Derivative liability	1,666	500
Derivative asset, netting	(4,433)	(2,325)
Derivative liability, netting	(4,403)	(2,277)
Commodity Contract [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	1,468	919
Derivative Liability, Gross Liability	1,721	1,004
Commodity Contract [Member] | Fair Value, Inputs, Level 2 [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	3,507	1,881
Derivative Liability, Gross Liability	3,412	1,468
Commodity Contract [Member] | Fair Value, Inputs, Level 3 [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	1,520	1,679
Derivative Liability, Gross Liability	936	305
Interest Rate Contract [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	85	40
Derivative liability	685	1,001
Derivative asset, netting	(39)	(41)
Derivative liability, netting	(39)	(41)
Interest Rate Contract [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	0	0
Derivative Liability, Gross Liability	0	0
Interest Rate Contract [Member] | Fair Value, Inputs, Level 2 [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	124	81
Derivative Liability, Gross Liability	724	1,042
Interest Rate Contract [Member] | Fair Value, Inputs, Level 3 [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	0	0
Derivative Liability, Gross Liability	0	0
Currency Swap [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	(4)	23
Derivative liability	37	9
Derivative asset, netting	(30)	(34)
Derivative liability, netting	(30)	(34)
Currency Swap [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	0	0
Derivative Liability, Gross Liability	0	0
Currency Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	26	57
Derivative Liability, Gross Liability	67	43
Currency Swap [Member] | Fair Value, Inputs, Level 3 [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	0	0
Derivative Liability, Gross Liability	0	0
FPL [Member]
Derivatives, Fair Value [Line Items]
Derivative liability		3
FPL [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	9	3
FPL [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Current	3	2
FPL [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Noncurrent		1
FPL [Member] | Commodity Contract [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative assets	9	3
Derivative liability	3	3
Derivative asset, netting	(2)	0
Derivative liability, netting	(2)	0
FPL [Member] | Commodity Contract [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	0	0
Derivative Liability, Gross Liability	0	0
FPL [Member] | Commodity Contract [Member] | Fair Value, Inputs, Level 2 [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	6	1
Derivative Liability, Gross Liability	0	0
FPL [Member] | Commodity Contract [Member] | Fair Value, Inputs, Level 3 [Member] | Fair value measurements made on a recurring basis [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross Asset	5	2
Derivative Liability, Gross Liability	$ 5	$ 3