Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	$ 2,156	$ 1,882
Gross Unrealized Holding Losses	88	83
Estimated Fair Value	6,554	6,214
NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2,115	1,846
Gross Unrealized Holding Losses	83	76
Estimated Fair Value	6,184	5,817
NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	111	179
NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2,092	1,823
Gross Unrealized Holding Losses	54	58
Estimated Fair Value	4,106	3,590
NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10	7
Gross Unrealized Holding Losses	8	8
Estimated Fair Value	528	432
NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	5
Gross Unrealized Holding Losses	10	1
Estimated Fair Value	331	185
NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10	11
Gross Unrealized Holding Losses	8	5
Estimated Fair Value	984	1,254
NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	3	4
Estimated Fair Value	124	177
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	41	36
Gross Unrealized Holding Losses	5	7
Estimated Fair Value	370	397
Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	25	29
Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	38	32
Gross Unrealized Holding Losses		1
Estimated Fair Value	104	95
Other Classification [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1	1
Gross Unrealized Holding Losses	1	3
Estimated Fair Value	66	92
Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	3
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	82	74
Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1
Estimated Fair Value	51	45
Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	2	2
Estimated Fair Value	42	62
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,165	1,028
Gross Unrealized Holding Losses	45	40
Estimated Fair Value	3,261	3,041
Duke Energy Carolinas [Member] | NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,165	1,028
Gross Unrealized Holding Losses	44	39
Estimated Fair Value	3,258	3,038
Duke Energy Carolinas [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	18	34
Duke Energy Carolinas [Member] | NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,157	1,021
Gross Unrealized Holding Losses	28	27
Estimated Fair Value	2,245	2,094
Duke Energy Carolinas [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5	3
Gross Unrealized Holding Losses	6	5
Estimated Fair Value	354	292
Duke Energy Carolinas [Member] | NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1	1
Gross Unrealized Holding Losses	2
Estimated Fair Value	67	33
Duke Energy Carolinas [Member] | NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	3
Gross Unrealized Holding Losses	5	3
Estimated Fair Value	458	438
Duke Energy Carolinas [Member] | NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	3	4
Estimated Fair Value	116	147
Duke Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	3	3
Duke Energy Carolinas [Member] | Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	3	3
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	952	821
Gross Unrealized Holding Losses	39	37
Estimated Fair Value	2,991	2,842
Progress Energy [Member] | NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	950	818
Gross Unrealized Holding Losses	39	37
Estimated Fair Value	2,926	2,779
Progress Energy [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	93	145
Progress Energy [Member] | NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	935	802
Gross Unrealized Holding Losses	26	31
Estimated Fair Value	1,861	1,496
Progress Energy [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5	4
Gross Unrealized Holding Losses	2	3
Estimated Fair Value	174	140
Progress Energy [Member] | NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	4
Gross Unrealized Holding Losses	8	1
Estimated Fair Value	264	152
Progress Energy [Member] | NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	8	8
Gross Unrealized Holding Losses	3	2
Estimated Fair Value	526	816
Progress Energy [Member] | NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	8	30
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	3
Estimated Fair Value	65	63
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	21	18
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	3
Estimated Fair Value	44	45
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	715	609
Gross Unrealized Holding Losses	32	30
Estimated Fair Value	2,214	2,039
Duke Energy Progress [Member] | NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	715	609
Gross Unrealized Holding Losses	32	30
Estimated Fair Value	2,213	2,038
Duke Energy Progress [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	45	110
Duke Energy Progress [Member] | NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	704	596
Gross Unrealized Holding Losses	21	25
Estimated Fair Value	1,505	1,178
Duke Energy Progress [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	3
Gross Unrealized Holding Losses	1	2
Estimated Fair Value	120	96
Duke Energy Progress [Member] | NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	4
Gross Unrealized Holding Losses	8	1
Estimated Fair Value	263	150
Duke Energy Progress [Member] | NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5	6
Gross Unrealized Holding Losses	2	2
Estimated Fair Value	275	486
Duke Energy Progress [Member] | NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	5	18
Duke Energy Progress [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	1
Duke Energy Progress [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	1
Duke Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	237	212
Gross Unrealized Holding Losses	7	7
Estimated Fair Value	761	792
Duke Energy Florida [Member] | NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	235	209
Gross Unrealized Holding Losses	7	7
Estimated Fair Value	713	741
Duke Energy Florida [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	48	35
Duke Energy Florida [Member] | NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	231	206
Gross Unrealized Holding Losses	5	6
Estimated Fair Value	356	318
Duke Energy Florida [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1	1
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	54	44
Duke Energy Florida [Member] | NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	2
Duke Energy Florida [Member] | NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Gross Unrealized Holding Losses	1
Estimated Fair Value	251	330
Duke Energy Florida [Member] | NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	3	12
Duke Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	3
Estimated Fair Value	48	51
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	4	6
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	3
Estimated Fair Value	44	45
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	33	27
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	110	101
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	33	27
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	110	101
Duke Energy Indiana [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value		2
Duke Energy Indiana [Member] | Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	33	27
Estimated Fair Value	79	71
Duke Energy Indiana [Member] | Other Classification [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	2	2
Duke Energy Indiana [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	28	$ 26
Duke Energy Indiana [Member] | Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	$ 1