Investments in Debt and Equity Securities (Estimated Fair Value of Investments in Debt and Equity Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale
Estimated Fair Value	$ 3,133
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	4,539	$ 5,033
Unrealized Holding Losses	202	66
Estimated Fair Value	10,371	10,893
Duke Energy Carolinas
Debt Securities, Available-for-sale
Estimated Fair Value	1,419
Progress Energy
Debt Securities, Available-for-sale
Estimated Fair Value	1,452
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,866	2,062
Unrealized Holding Losses	92	36
Estimated Fair Value	4,428	4,688
Duke Energy Progress
Debt Securities, Available-for-sale
Estimated Fair Value	1,031
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,768	1,957
Unrealized Holding Losses	74	29
Estimated Fair Value	3,885	4,105
Duke Energy Florida
Debt Securities, Available-for-sale
Estimated Fair Value	421
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	98	105
Unrealized Holding Losses	18	7
Estimated Fair Value	542	582
Duke Energy Indiana
Debt Securities, Available-for-sale
Estimated Fair Value	63
NDTF
Available-for-sale Securities
Cash and cash equivalents	128	160
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	4,486	4,905
Equity Securities, FV-NI, Accumulated Unrealized Loss	62	43
Equity securities, FV-NI	6,853	7,350
Debt Securities, Available-for-sale
Estimated Fair Value	2,845	2,891
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	4,507	4,992
Unrealized Holding Losses	185	63
Estimated Fair Value	9,826	10,401
NDTF | Duke Energy Carolinas
Available-for-sale Securities
Cash and cash equivalents	60	53
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	2,632	2,887
Equity Securities, FV-NI, Accumulated Unrealized Loss	30	19
Equity securities, FV-NI	3,962	4,265
Debt Securities, Available-for-sale
Estimated Fair Value	1,419	1,441
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	2,642	2,932
Unrealized Holding Losses	93	27
Estimated Fair Value	5,441	5,759
NDTF | Progress Energy
Available-for-sale Securities
Cash and cash equivalents	68	107
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,854	2,018
Equity Securities, FV-NI, Accumulated Unrealized Loss	32	24
Equity securities, FV-NI	2,891	3,085
Debt Securities, Available-for-sale
Estimated Fair Value	1,426	1,450
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,865	2,060
Unrealized Holding Losses	92	36
Estimated Fair Value	4,385	4,642
NDTF | Duke Energy Progress
Available-for-sale Securities
Cash and cash equivalents	58	94
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,757	1,915
Equity Securities, FV-NI, Accumulated Unrealized Loss	32	23
Equity securities, FV-NI	2,782	2,970
Debt Securities, Available-for-sale
Estimated Fair Value	1,031	1,025
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1,768	1,957
Unrealized Holding Losses	74	29
Estimated Fair Value	3,871	4,089
NDTF | Duke Energy Florida
Available-for-sale Securities
Cash and cash equivalents	10	13
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	97	103
Equity Securities, FV-NI, Accumulated Unrealized Loss		1
Equity securities, FV-NI	109	115
Debt Securities, Available-for-sale
Estimated Fair Value	395	425
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	97	103
Unrealized Holding Losses	18	7
Estimated Fair Value	514	553
Other Investments
Available-for-sale Securities
Cash and cash equivalents	110	36
Equity Securities, FV-NI
Equity Securities, FV-NI, Accumulated Unrealized Gain	31	36
Equity Securities, FV-NI, Accumulated Unrealized Loss	4
Equity securities, FV-NI	147	156
Debt Securities, Available-for-sale
Estimated Fair Value	288	300
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	32	41
Unrealized Holding Losses	17	3
Estimated Fair Value	545	492
Other Investments | Progress Energy
Available-for-sale Securities
Cash and cash equivalents	17	20
Debt Securities, Available-for-sale
Estimated Fair Value	26	26
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1	2
Estimated Fair Value	43	46
Other Investments | Duke Energy Progress
Available-for-sale Securities
Cash and cash equivalents	14	16
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Estimated Fair Value	14	16
Other Investments | Duke Energy Florida
Available-for-sale Securities
Cash and cash equivalents	2	3
Debt Securities, Available-for-sale
Estimated Fair Value	26	26
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	1	2
Estimated Fair Value	28	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	4	6
Equity Securities, FV-NI, Accumulated Unrealized Loss	4
Equity securities, FV-NI	91	97
Debt Securities, Available-for-sale
Estimated Fair Value	63	64
Investments, Accumulated Gross Unrealized Gains (Losses) [Abstract]
Unrealized Holding Gains	4	7
Unrealized Holding Losses	6	1
Estimated Fair Value	155	161
Corporate debt securities | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	9	39
Gross Unrealized Holding Losses	43	6
Estimated Fair Value	786	829
Corporate debt securities | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	6	24
Gross Unrealized Holding Losses	30	4
Estimated Fair Value	503	506
Corporate debt securities | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	3	15
Gross Unrealized Holding Losses	13	2
Estimated Fair Value	283	323
Corporate debt securities | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	3	15
Gross Unrealized Holding Losses	12	2
Estimated Fair Value	255	282
Corporate debt securities | NDTF | Duke Energy Florida
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	28	41
Corporate debt securities | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses	7	1
Estimated Fair Value	124	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	2	14
Gross Unrealized Holding Losses	16	1
Estimated Fair Value	321	314
Municipal bonds | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses	5
Estimated Fair Value	52	48
Municipal bonds | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2	12
Gross Unrealized Holding Losses	11	1
Estimated Fair Value	269	266
Municipal bonds | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2	12
Gross Unrealized Holding Losses	11	1
Estimated Fair Value	269	266
Municipal bonds | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1	3
Gross Unrealized Holding Losses	2	1
Estimated Fair Value	83	80
Municipal bonds | Other Investments | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1	2
Estimated Fair Value	26	26
Municipal bonds | Other Investments | Duke Energy Florida
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1	2
Estimated Fair Value	26	26
Municipal bonds | Other Investments | Duke Energy Indiana
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		1
Gross Unrealized Holding Losses	2	1
Estimated Fair Value	49	46
U.S. government bonds | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	10	31
Gross Unrealized Holding Losses	57	12
Estimated Fair Value	1,561	1,568
U.S. government bonds | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	4	16
Gross Unrealized Holding Losses	21	3
Estimated Fair Value	692	712
U.S. government bonds | NDTF | Progress Energy
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	6	15
Gross Unrealized Holding Losses	36	9
Estimated Fair Value	869	856
U.S. government bonds | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	6	15
Gross Unrealized Holding Losses	19	3
Estimated Fair Value	502	472
U.S. government bonds | NDTF | Duke Energy Florida
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	17	6
Estimated Fair Value	367	384
U.S. government bonds | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	2
Estimated Fair Value	45	56
U.S. government bonds | Other Investments | Duke Energy Indiana
Debt Securities, Available-for-sale
Estimated Fair Value	6	12
Other debt securities | NDTF
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses	7	1
Estimated Fair Value	177	180
Other debt securities | NDTF | Duke Energy Carolinas
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses	7	1
Estimated Fair Value	172	175
Other debt securities | NDTF | Progress Energy
Debt Securities, Available-for-sale
Estimated Fair Value	5	5
Other debt securities | NDTF | Duke Energy Progress
Debt Securities, Available-for-sale
Estimated Fair Value	5	5
Other debt securities | Other Investments
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	2	1
Estimated Fair Value	$ 36	$ 45