Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	$ 2,079	$ 1,882
Gross Unrealized Holding Losses	64	83
Estimated Fair Value	6,519	6,214
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2,033	1,846
Gross Unrealized Holding Losses	61	76
Estimated Fair Value	6,118	5,817
Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	151	179
Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,968	1,823
Gross Unrealized Holding Losses	55	58
Estimated Fair Value	3,949	3,590
Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	25	7
Gross Unrealized Holding Losses	2	8
Estimated Fair Value	551	432
Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	9	5
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	341	185
Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	31	11
Gross Unrealized Holding Losses		5
Estimated Fair Value	994	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	132	177
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	46	36
Gross Unrealized Holding Losses	3	7
Estimated Fair Value	401	397
Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	24	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	2	1
Gross Unrealized Holding Losses	1	3
Estimated Fair Value	91	92
Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5	3
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	78	74
Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1
Estimated Fair Value	49	45
Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	2
Estimated Fair Value	55	62
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,119	1,028
Gross Unrealized Holding Losses	35	40
Estimated Fair Value	3,233	3,041
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,119	1,028
Gross Unrealized Holding Losses	34	39
Estimated Fair Value	3,230	3,038
Duke Energy Carolinas [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	43	34
Duke Energy Carolinas [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,091	1,021
Gross Unrealized Holding Losses	29	27
Estimated Fair Value	2,170	2,094
Duke Energy Carolinas [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	14	3
Gross Unrealized Holding Losses	2	5
Estimated Fair Value	374	292
Duke Energy Carolinas [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	1
Estimated Fair Value	66	33
Duke Energy Carolinas [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	12	3
Gross Unrealized Holding Losses		3
Estimated Fair Value	454	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	123	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	918	821
Gross Unrealized Holding Losses	27	37
Estimated Fair Value	2,955	2,842
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	914	818
Gross Unrealized Holding Losses	27	37
Estimated Fair Value	2,888	2,779
Progress Energy [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	108	145
Progress Energy [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	877	802
Gross Unrealized Holding Losses	26	31
Estimated Fair Value	1,779	1,496
Progress Energy [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	11	4
Gross Unrealized Holding Losses		3
Estimated Fair Value	177	140
Progress Energy [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	7	4
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	275	152
Progress Energy [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	19	8
Gross Unrealized Holding Losses		2
Estimated Fair Value	540	816
Progress Energy [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	9	30
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	3
Estimated Fair Value	67	63
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	20	18
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	3
Estimated Fair Value	47	45
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	684	609
Gross Unrealized Holding Losses	22	30
Estimated Fair Value	2,178	2,039
Duke Energy Progress [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	684	609
Gross Unrealized Holding Losses	22	30
Estimated Fair Value	2,177	2,038
Duke Energy Progress [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	56	110
Duke Energy Progress [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	657	596
Gross Unrealized Holding Losses	21	25
Estimated Fair Value	1,438	1,178
Duke Energy Progress [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	8	3
Gross Unrealized Holding Losses		2
Estimated Fair Value	123	96
Duke Energy Progress [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	7	4
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	275	150
Duke Energy Progress [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	12	6
Gross Unrealized Holding Losses	0	2
Estimated Fair Value	279	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]
Gross Unrealized Holding Gains	234	212
Gross Unrealized Holding Losses	5	7
Estimated Fair Value	760	792
Duke Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	230	209
Gross Unrealized Holding Losses	5	7
Estimated Fair Value	711	741
Duke Energy Florida [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	52	35
Duke Energy Florida [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	220	206
Gross Unrealized Holding Losses	5	6
Estimated Fair Value	341	318
Duke Energy Florida [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	1
Gross Unrealized Holding Losses		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		2
Duke Energy Florida [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	7	2
Estimated Fair Value	261	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	4	3
Estimated Fair Value	49	51
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	2	6
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	3
Estimated Fair Value	47	45
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	32	27
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	107	101
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	32	27
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	107	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	31	27
Estimated Fair Value	77	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 Gains	1
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	$ 28	$ 26