Investments in Debt and Equity Securities (Estimated Fair Value of Investments in Debt and Equity Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale
Estimated Fair Value	$ 3,191
Total Investments
Unrealized Holding Gains	5,033	$ 4,387
Unrealized Holding Losses	66	55
Estimated Fair Value	10,893	9,687
NDTF
Equity Securities, FV-NI
Gross Unrealized Holding Gains	4,905	4,138
Gross Unrealized Holding Losses	43	54
Estimated Fair Value	7,350	6,235
Debt Securities, Available-for-sale
Estimated Fair Value	2,891	2,717
Total Investments
Unrealized Holding Gains	4,992	4,295
Unrealized Holding Losses	63	55
Estimated Fair Value	10,401	9,129
NDTF | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	160	177
NDTF | Corporate debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	39	76
Gross Unrealized Holding Losses	6	1
Estimated Fair Value	829	806
NDTF | Municipal bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	14	22
Gross Unrealized Holding Losses	1
Estimated Fair Value	314	370
NDTF | U.S. government bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	31	51
Gross Unrealized Holding Losses	12
Estimated Fair Value	1,568	1,361
NDTF | Other debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	3	8
Gross Unrealized Holding Losses	1
Estimated Fair Value	180	180
Other Investments
Equity Securities, FV-NI
Gross Unrealized Holding Gains	36	79
Estimated Fair Value	156	146
Debt Securities, Available-for-sale
Estimated Fair Value	300	285
Total Investments
Unrealized Holding Gains	41	92
Unrealized Holding Losses	3
Estimated Fair Value	492	558
Other Investments | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	36	127
Other Investments | Corporate debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2	8
Gross Unrealized Holding Losses	1
Estimated Fair Value	119	110
Other Investments | Municipal bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	3	5
Gross Unrealized Holding Losses	1
Estimated Fair Value	80	86
Other Investments | U.S. government bonds
Debt Securities, Available-for-sale
Estimated Fair Value	56	42
Other Investments | Other debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	45	47
Duke Energy Carolinas
Debt Securities, Available-for-sale
Estimated Fair Value	1,441
Duke Energy Carolinas | NDTF
Equity Securities, FV-NI
Gross Unrealized Holding Gains	2,887	2,442
Gross Unrealized Holding Losses	19	23
Estimated Fair Value	4,265	3,685
Debt Securities, Available-for-sale
Estimated Fair Value	1,441	1,250
Total Investments
Unrealized Holding Gains	2,932	2,529
Unrealized Holding Losses	27	24
Estimated Fair Value	5,759	4,965
Duke Energy Carolinas | NDTF | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	53	30
Duke Energy Carolinas | NDTF | Corporate debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	24	49
Gross Unrealized Holding Losses	4	1
Estimated Fair Value	506	510
Duke Energy Carolinas | NDTF | Municipal bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2	6
Estimated Fair Value	48	91
Duke Energy Carolinas | NDTF | U.S. government bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	16	25
Gross Unrealized Holding Losses	3
Estimated Fair Value	712	475
Duke Energy Carolinas | NDTF | Other debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	3	7
Gross Unrealized Holding Losses	1
Estimated Fair Value	175	174
Progress Energy
Debt Securities, Available-for-sale
Estimated Fair Value	1,476
Total Investments
Unrealized Holding Gains	2,062	1,769
Unrealized Holding Losses	36	31
Estimated Fair Value	4,688	4,296
Progress Energy | NDTF
Equity Securities, FV-NI
Gross Unrealized Holding Gains	2,018	1,696
Gross Unrealized Holding Losses	24	31
Estimated Fair Value	3,085	2,550
Debt Securities, Available-for-sale
Estimated Fair Value	1,450	1,467
Total Investments
Unrealized Holding Gains	2,060	1,766
Unrealized Holding Losses	36	31
Estimated Fair Value	4,642	4,164
Progress Energy | NDTF | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	107	147
Progress Energy | NDTF | Corporate debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	15	27
Gross Unrealized Holding Losses	2
Estimated Fair Value	323	296
Progress Energy | NDTF | Municipal bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	12	16
Gross Unrealized Holding Losses	1
Estimated Fair Value	266	279
Progress Energy | NDTF | U.S. government bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	15	26
Gross Unrealized Holding Losses	9
Estimated Fair Value	856	886
Progress Energy | NDTF | Other debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		1
Estimated Fair Value	5	6
Progress Energy | Other Investments
Debt Securities, Available-for-sale
Estimated Fair Value	26	26
Total Investments
Unrealized Holding Gains	2	3
Estimated Fair Value	46	132
Progress Energy | Other Investments | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	20	106
Progress Energy | Other Investments | Municipal bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2	3
Estimated Fair Value	26	26
Duke Energy Progress
Debt Securities, Available-for-sale
Estimated Fair Value	1,025
Total Investments
Unrealized Holding Gains	1,957	1,687
Unrealized Holding Losses	29	31
Estimated Fair Value	4,105	3,529
Duke Energy Progress | NDTF
Equity Securities, FV-NI
Gross Unrealized Holding Gains	1,915	1,617
Gross Unrealized Holding Losses	23	31
Estimated Fair Value	2,970	2,459
Debt Securities, Available-for-sale
Estimated Fair Value	1,025	993
Total Investments
Unrealized Holding Gains	1,957	1,687
Unrealized Holding Losses	29	31
Estimated Fair Value	4,089	3,528
Duke Energy Progress | NDTF | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	94	76
Duke Energy Progress | NDTF | Corporate debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	15	27
Gross Unrealized Holding Losses	2
Estimated Fair Value	282	296
Duke Energy Progress | NDTF | Municipal bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	12	16
Gross Unrealized Holding Losses	1
Estimated Fair Value	266	279
Duke Energy Progress | NDTF | U.S. government bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	15	26
Gross Unrealized Holding Losses	3
Estimated Fair Value	472	412
Duke Energy Progress | NDTF | Other debt securities
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		1
Estimated Fair Value	5	6
Duke Energy Progress | Other Investments
Total Investments
Estimated Fair Value	16	1
Duke Energy Progress | Other Investments | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	16	1
Duke Energy Florida
Debt Securities, Available-for-sale
Estimated Fair Value	451
Total Investments
Unrealized Holding Gains	105	82
Unrealized Holding Losses	7
Estimated Fair Value	582	663
Duke Energy Florida | NDTF
Equity Securities, FV-NI
Gross Unrealized Holding Gains	103	79
Gross Unrealized Holding Losses	1
Estimated Fair Value	115	91
Debt Securities, Available-for-sale
Estimated Fair Value	425	474
Total Investments
Unrealized Holding Gains	103	79
Unrealized Holding Losses	7
Estimated Fair Value	553	636
Duke Energy Florida | NDTF | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	13	71
Duke Energy Florida | NDTF | Corporate debt securities
Debt Securities, Available-for-sale
Estimated Fair Value	41
Duke Energy Florida | NDTF | U.S. government bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	6
Estimated Fair Value	384	474
Duke Energy Florida | Other Investments
Debt Securities, Available-for-sale
Estimated Fair Value	26	26
Total Investments
Unrealized Holding Gains	2	3
Estimated Fair Value	29	27
Duke Energy Florida | Other Investments | Cash and cash equivalents
Available-for-sale Securities
Cash and cash equivalents	3	1
Duke Energy Florida | Other Investments | Municipal bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2	3
Estimated Fair Value	26	26
Duke Energy Indiana
Debt Securities, Available-for-sale
Estimated Fair Value	64
Total Investments
Unrealized Holding Gains	7	59
Unrealized Holding Losses	1
Estimated Fair Value	161	143
Duke Energy Indiana | Other Investments
Available-for-sale Securities
Cash and cash equivalents		1
Equity Securities, FV-NI
Gross Unrealized Holding Gains	6	58
Estimated Fair Value	97	97
Debt Securities, Available-for-sale
Estimated Fair Value	64	45
Duke Energy Indiana | Other Investments | Corporate debt securities
Debt Securities, Available-for-sale
Estimated Fair Value	6	3
Duke Energy Indiana | Other Investments | Municipal bonds
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1	1
Gross Unrealized Holding Losses	1
Estimated Fair Value	46	38
Duke Energy Indiana | Other Investments | U.S. government bonds
Debt Securities, Available-for-sale
Estimated Fair Value	$ 12	$ 4