Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Gains	$ 1,918	$ 1,882
Gross Unrealized Holding Losses	77	83
Estimated Fair Value	6,298	6,214
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1,879	1,846
Gross Unrealized Holding Losses	71	76
Estimated Fair Value	5,894	5,817
Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	201	179
Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1,823	1,823
Gross Unrealized Holding Losses	64	58
Estimated Fair Value	3,592	3,590
Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	16	7
Gross Unrealized Holding Losses	3	8
Estimated Fair Value	454	432
Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	6	5
Gross Unrealized Holding Losses		1
Estimated Fair Value	211	185
Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	33	11
Gross Unrealized Holding Losses		5
Estimated Fair Value	1,288	1,254
Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1
Gross Unrealized Holding Losses	4	4
Estimated Fair Value	148	177
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	39	36
Gross Unrealized Holding Losses	6	7
Estimated Fair Value	404	397
Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	29	29
Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	33	32
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	97	95
Other Classification [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1	1
Gross Unrealized Holding Losses	2	3
Estimated Fair Value	91	92
Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	3	3
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	76	74
Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	2
Estimated Fair Value	56	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	55	62
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1,044	1,028
Gross Unrealized Holding Losses	38	40
Estimated Fair Value	3,091	3,041
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1,044	1,028
Gross Unrealized Holding Losses	37	39
Estimated Fair Value	3,088	3,038
Duke Energy Carolinas [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	50	34
Duke Energy Carolinas [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1,022	1,021
Gross Unrealized Holding Losses	31	27
Estimated Fair Value	2,088	2,094
Duke Energy Carolinas [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	8	3
Gross Unrealized Holding Losses	2	5
Estimated Fair Value	257	292
Duke Energy Carolinas [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1	1
Gross Unrealized Holding Losses	0
Estimated Fair Value	53	33
Duke Energy Carolinas [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	12	3
Gross Unrealized Holding Losses	0	3
Estimated Fair Value	502	438
Duke Energy Carolinas [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	1
Gross Unrealized Holding Losses	4	4
Estimated Fair Value	138	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]
Gains	838	821
Gross Unrealized Holding Losses	34	37
Estimated Fair Value	2,869	2,842
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	835	818
Gross Unrealized Holding Losses	34	37
Estimated Fair Value	2,806	2,779
Progress Energy [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	151	145
Progress Energy [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	801	802
Gross Unrealized Holding Losses	33	31
Estimated Fair Value	1,504	1,496
Progress Energy [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	8	4
Gross Unrealized Holding Losses	1	3
Estimated Fair Value	197	140
Progress Energy [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	5	4
Gross Unrealized Holding Losses		1
Estimated Fair Value	158	152
Progress Energy [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	21	8
Gross Unrealized Holding Losses		2
Estimated Fair Value	786	816
Progress Energy [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	10	30
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	3	3
Estimated Fair Value	63	63
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	17	18
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	3	3
Estimated Fair Value	46	45
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	621	609
Gross Unrealized Holding Losses	28	30
Estimated Fair Value	2,073	2,039
Duke Energy Progress [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	621	609
Gross Unrealized Holding Losses	28	30
Estimated Fair Value	2,072	2,038
Duke Energy Progress [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	100	110
Duke Energy Progress [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	595	596
Gross Unrealized Holding Losses	27	25
Estimated Fair Value	1,184	1,178
Duke Energy Progress [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	6	3
Gross Unrealized Holding Losses	1	2
Estimated Fair Value	145	96
Duke Energy Progress [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	5	4
Gross Unrealized Holding Losses		1
Estimated Fair Value	158	150
Duke Energy Progress [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	15	6
Gross Unrealized Holding Losses		2
Estimated Fair Value	479	486
Duke Energy Progress [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	6	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]
Gains	217	212
Gross Unrealized Holding Losses	6	7
Estimated Fair Value	781	792
Duke Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	214	209
Gross Unrealized Holding Losses	6	7
Estimated Fair Value	734	741
Duke Energy Florida [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	51	35
Duke Energy Florida [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	206	206
Gross Unrealized Holding Losses	6	6
Estimated Fair Value	320	318
Duke Energy Florida [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	2	1
Gross Unrealized Holding Losses		1
Estimated Fair Value	52	44
Duke Energy Florida [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	0	2
Duke Energy Florida [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	6	2
Estimated Fair Value	307	330
Duke Energy Florida [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	4	12
Duke Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	3	3
Estimated Fair Value	47	51
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	6
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	3	3
Estimated Fair Value	46	45
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	27	27
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	102	101
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	27	27
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	102	101
Duke Energy Indiana [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	2
Duke Energy Indiana [Member] | Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gains	27	27
Estimated Fair Value	72	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	$ 27	$ 26