Investments in Debt and Equity Securities (Estimated Fair Value of Investments in Debt and Equity Securities) (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale
Estimated Fair Value	$ 2,968
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	3,522	$ 5,033
Unrealized Holding Losses	397	66
Estimated Fair Value	9,028	10,893
Duke Energy Carolinas
Debt Securities, Available-for-sale
Estimated Fair Value	1,343
Progress Energy
Debt Securities, Available-for-sale
Estimated Fair Value	1,376
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,443	2,062
Unrealized Holding Losses	166	36
Estimated Fair Value	3,891	4,688
Duke Energy Progress
Debt Securities, Available-for-sale
Estimated Fair Value	994
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,364	1,957
Unrealized Holding Losses	144	29
Estimated Fair Value	3,385	4,105
Duke Energy Florida
Debt Securities, Available-for-sale
Estimated Fair Value	382
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	79	105
Unrealized Holding Losses	22	7
Estimated Fair Value	504	582
Duke Energy Indiana
Debt Securities, Available-for-sale
Estimated Fair Value	61
NDTF
Available-for-sale Securities
Cash and cash equivalents	134	160
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	3,500	4,905
Equity Securities, FV-NI, Accumulated Unrealized Loss	141	43
Equity securities, FV-NI	5,751	7,350
Debt Securities, Available-for-sale
Estimated Fair Value	2,694	2,891
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	3,502	4,992
Unrealized Holding Losses	357	63
Estimated Fair Value	8,579	10,401
NDTF | Duke Energy Carolinas
Available-for-sale Securities
Cash and cash equivalents	58	53
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	2,058	2,887
Equity Securities, FV-NI, Accumulated Unrealized Loss	69	19
Equity securities, FV-NI	3,327	4,265
Debt Securities, Available-for-sale
Estimated Fair Value	1,343	1,441
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	2,059	2,932
Unrealized Holding Losses	191	27
Estimated Fair Value	4,728	5,759
NDTF | Progress Energy
Available-for-sale Securities
Cash and cash equivalents	76	107
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,442	2,018
Equity Securities, FV-NI, Accumulated Unrealized Loss	72	24
Equity securities, FV-NI	2,424	3,085
Debt Securities, Available-for-sale
Estimated Fair Value	1,351	1,450
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,443	2,060
Unrealized Holding Losses	166	36
Estimated Fair Value	3,851	4,642
NDTF | Duke Energy Progress
Available-for-sale Securities
Cash and cash equivalents	46	94
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,363	1,915
Equity Securities, FV-NI, Accumulated Unrealized Loss	72	23
Equity securities, FV-NI	2,333	2,970
Debt Securities, Available-for-sale
Estimated Fair Value	994	1,025
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,364	1,957
Unrealized Holding Losses	144	29
Estimated Fair Value	3,373	4,089
NDTF | Duke Energy Florida
Available-for-sale Securities
Cash and cash equivalents	30	13
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	79	103
Equity Securities, FV-NI, Accumulated Unrealized Loss		1
Equity securities, FV-NI	91	115
Debt Securities, Available-for-sale
Estimated Fair Value	357	425
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	79	103
Unrealized Holding Losses	22	7
Estimated Fair Value	478	553
Other Investments
Available-for-sale Securities
Cash and cash equivalents	51	36
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	20	36
Equity Securities, FV-NI, Accumulated Unrealized Loss	17
Equity securities, FV-NI	124	156
Debt Securities, Available-for-sale
Estimated Fair Value	274	300
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	20	41
Unrealized Holding Losses	40	3
Estimated Fair Value	449	492
Other Investments | Progress Energy
Available-for-sale Securities
Cash and cash equivalents	15	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	40	46
Other Investments | Duke Energy Progress
Available-for-sale Securities
Cash and cash equivalents	12	16
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Estimated Fair Value	12	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
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	2	6
Equity Securities, FV-NI, Accumulated Unrealized Loss	17
Equity securities, FV-NI	77	97
Debt Securities, Available-for-sale
Estimated Fair Value	61	64
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	2	7
Unrealized Holding Losses	20	1
Estimated Fair Value	138	161
Corporate debt securities | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		39
Gross Unrealized Holding Losses	81	6
Estimated Fair Value	728	829
Corporate debt securities | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		24
Gross Unrealized Holding Losses	63	4
Estimated Fair Value	470	506
Corporate debt securities | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		15
Gross Unrealized Holding Losses	18	2
Estimated Fair Value	258	323
Corporate debt securities | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		15
Gross Unrealized Holding Losses	17	2
Estimated Fair Value	241	282
Corporate debt securities | NDTF | Duke Energy Florida
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	17	41
Corporate debt securities | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses	13	1
Estimated Fair Value	108	119
Corporate debt securities | Other Investments | Duke Energy Indiana
Debt Securities, Available-for-sale
Estimated Fair Value	8	6
Municipal bonds | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		14
Gross Unrealized Holding Losses	32	1
Estimated Fair Value	334	314
Municipal bonds | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses	9
Estimated Fair Value	63	48
Municipal bonds | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		12
Gross Unrealized Holding Losses	23	1
Estimated Fair Value	271	266
Municipal bonds | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		12
Gross Unrealized Holding Losses	23	1
Estimated Fair Value	271	266
Municipal bonds | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses	3	1
Estimated Fair Value	82	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	3	1
Estimated Fair Value	48	46
U.S. government bonds | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2	31
Gross Unrealized Holding Losses	89	12
Estimated Fair Value	1,462	1,568
U.S. government bonds | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1	16
Gross Unrealized Holding Losses	37	3
Estimated Fair Value	645	712
U.S. government bonds | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1	15
Gross Unrealized Holding Losses	52	9
Estimated Fair Value	817	856
U.S. government bonds | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1	15
Gross Unrealized Holding Losses	31	3
Estimated Fair Value	477	472
U.S. government bonds | NDTF | Duke Energy Florida
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	21	6
Estimated Fair Value	340	384
U.S. government bonds | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	5
Estimated Fair Value	49	56
U.S. government bonds | Other Investments | Duke Energy Indiana
Debt Securities, Available-for-sale
Estimated Fair Value	5	12
Other debt securities | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses	14	1
Estimated Fair Value	170	180
Other debt securities | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses	13	1
Estimated Fair Value	165	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	2	1
Estimated Fair Value	$ 35	$ 45