Investments in Debt and Equity Securities (Estimated Fair Value of Investments in Debt and Equity Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale
Estimated Fair Value	$ 2,820
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	3,253	$ 5,033
Unrealized Holding Losses	547	66
Estimated Fair Value	8,540	10,893
Duke Energy Carolinas
Debt Securities, Available-for-sale
Estimated Fair Value	1,286
Progress Energy
Debt Securities, Available-for-sale
Estimated Fair Value	1,295
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,335	2,062
Unrealized Holding Losses	235	36
Estimated Fair Value	3,680	4,688
Duke Energy Progress
Debt Securities, Available-for-sale
Estimated Fair Value	951
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,261	1,957
Unrealized Holding Losses	207	29
Estimated Fair Value	3,215	4,105
Duke Energy Florida
Debt Securities, Available-for-sale
Estimated Fair Value	344
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	74	105
Unrealized Holding Losses	28	7
Estimated Fair Value	464	582
Duke Energy Indiana
Debt Securities, Available-for-sale
Estimated Fair Value	59
NDTF
Available-for-sale Securities
Cash and cash equivalents	120	160
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	3,238	4,905
Equity Securities, FV-NI, Accumulated Unrealized Loss	181	43
Equity securities, FV-NI	5,447	7,350
Debt Securities, Available-for-sale
Estimated Fair Value	2,556	2,891
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	3,238	4,992
Unrealized Holding Losses	505	63
Estimated Fair Value	8,123	10,401
NDTF | Duke Energy Carolinas
Available-for-sale Securities
Cash and cash equivalents	41	53
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,903	2,887
Equity Securities, FV-NI, Accumulated Unrealized Loss	87	19
Equity securities, FV-NI	3,154	4,265
Debt Securities, Available-for-sale
Estimated Fair Value	1,286	1,441
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,903	2,932
Unrealized Holding Losses	270	27
Estimated Fair Value	4,481	5,759
NDTF | Progress Energy
Available-for-sale Securities
Cash and cash equivalents	79	107
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,335	2,018
Equity Securities, FV-NI, Accumulated Unrealized Loss	94	24
Equity securities, FV-NI	2,293	3,085
Debt Securities, Available-for-sale
Estimated Fair Value	1,270	1,450
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,335	2,060
Unrealized Holding Losses	235	36
Estimated Fair Value	3,642	4,642
NDTF | Duke Energy Progress
Available-for-sale Securities
Cash and cash equivalents	47	94
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,261	1,915
Equity Securities, FV-NI, Accumulated Unrealized Loss	94	23
Equity securities, FV-NI	2,206	2,970
Debt Securities, Available-for-sale
Estimated Fair Value	951	1,025
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,261	1,957
Unrealized Holding Losses	207	29
Estimated Fair Value	3,204	4,089
NDTF | Duke Energy Florida
Available-for-sale Securities
Cash and cash equivalents	32	13
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	74	103
Equity Securities, FV-NI, Accumulated Unrealized Loss		1
Equity securities, FV-NI	87	115
Debt Securities, Available-for-sale
Estimated Fair Value	319	425
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	74	103
Unrealized Holding Losses	28	7
Estimated Fair Value	438	553
Other Investments
Available-for-sale Securities
Cash and cash equivalents	37	36
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	15	36
Equity Securities, FV-NI, Accumulated Unrealized Loss	20
Equity securities, FV-NI	116	156
Debt Securities, Available-for-sale
Estimated Fair Value	264	300
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	15	41
Unrealized Holding Losses	42	3
Estimated Fair Value	417	492
Other Investments | Progress Energy
Available-for-sale Securities
Cash and cash equivalents	13	20
Debt Securities, Available-for-sale
Estimated Fair Value	25	26
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains		2
Estimated Fair Value	38	46
Other Investments | Duke Energy Progress
Available-for-sale Securities
Cash and cash equivalents	11	16
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Estimated Fair Value	11	16
Other Investments | Duke Energy Florida
Available-for-sale Securities
Cash and cash equivalents	1	3
Debt Securities, Available-for-sale
Estimated Fair Value	25	26
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains		2
Estimated Fair Value	26	29
Other Investments | Duke Energy Indiana
Available-for-sale Securities
Cash and cash equivalents	1
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain		6
Equity Securities, FV-NI, Accumulated Unrealized Loss	20
Equity securities, FV-NI	72	97
Debt Securities, Available-for-sale
Estimated Fair Value	59	64
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains		7
Unrealized Holding Losses	25	1
Estimated Fair Value	132	161
Corporate debt securities | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		39
Gross Unrealized Holding Losses	116	6
Estimated Fair Value	682	829
Corporate debt securities | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		24
Gross Unrealized Holding Losses	86	4
Estimated Fair Value	433	506
Corporate debt securities | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		15
Gross Unrealized Holding Losses	30	2
Estimated Fair Value	249	323
Corporate debt securities | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		15
Gross Unrealized Holding Losses	29	2
Estimated Fair Value	234	282
Corporate debt securities | NDTF | Duke Energy Florida
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	15	41
Corporate debt securities | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses	14	1
Estimated Fair Value	81	119
Corporate debt securities | Other Investments | Duke Energy Indiana
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	7	6
Municipal bonds | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		14
Gross Unrealized Holding Losses	49	1
Estimated Fair Value	319	314
Municipal bonds | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses	13
Estimated Fair Value	57	48
Municipal bonds | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		12
Gross Unrealized Holding Losses	36	1
Estimated Fair Value	262	266
Municipal bonds | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		12
Gross Unrealized Holding Losses	36	1
Estimated Fair Value	262	266
Municipal bonds | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses	4	1
Estimated Fair Value	80	80
Municipal bonds | Other Investments | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		2
Estimated Fair Value	25	26
Municipal bonds | Other Investments | Duke Energy Florida
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		2
Estimated Fair Value	25	26
Municipal bonds | Other Investments | Duke Energy Indiana
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		1
Gross Unrealized Holding Losses	4	1
Estimated Fair Value	45	46
U.S. government bonds | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		31
Gross Unrealized Holding Losses	139	12
Estimated Fair Value	1,391	1,568
U.S. government bonds | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		16
Gross Unrealized Holding Losses	65	3
Estimated Fair Value	637	712
U.S. government bonds | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		15
Gross Unrealized Holding Losses	74	9
Estimated Fair Value	754	856
U.S. government bonds | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		15
Gross Unrealized Holding Losses	47	3
Estimated Fair Value	450	472
U.S. government bonds | NDTF | Duke Energy Florida
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	27	6
Estimated Fair Value	304	384
U.S. government bonds | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	63	56
U.S. government bonds | Other Investments | Duke Energy Indiana
Debt Securities, Available-for-sale
Estimated Fair Value	7	12
Other debt securities | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses	20	1
Estimated Fair Value	164	180
Other debt securities | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses	19	1
Estimated Fair Value	159	175
Other debt securities | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	5	5
Other debt securities | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	5	5
Other debt securities | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	3	1
Estimated Fair Value	$ 40	$ 45