Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	$ 2,455	$ 2,156
Gross Unrealized Holding Losses	42	88
Estimated Fair Value	6,947	6,554
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2,404	2,115
Gross Unrealized Holding Losses	41	83
Estimated Fair Value	6,592	6,184
Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	116	111
Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2,373	2,092
Gross Unrealized Holding Losses	29	54
Estimated Fair Value	4,422	4,106
Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	15	10
Gross Unrealized Holding Losses	2	8
Estimated Fair Value	611	528
Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	3
Gross Unrealized Holding Losses	3	10
Estimated Fair Value	340	331
Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	12	10
Gross Unrealized Holding Losses	6	8
Estimated Fair Value	961	984
Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	3
Estimated Fair Value	142	124
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	51	41
Gross Unrealized Holding Losses	1	5
Estimated Fair Value	355	370
Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	15	25
Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	47	38
Estimated Fair Value	110	104
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
Estimated Fair Value	63	66
Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	82	82
Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses		1
Estimated Fair Value	49	51
Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses		2
Estimated Fair Value	36	42
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,312	1,165
Gross Unrealized Holding Losses	21	45
Estimated Fair Value	3,490	3,261
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,312	1,165
Gross Unrealized Holding Losses	21	44
Estimated Fair Value	3,490	3,258
Duke Energy Carolinas [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	33	18
Duke Energy Carolinas [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,299	1,157
Gross Unrealized Holding Losses	14	28
Estimated Fair Value	2,441	2,245
Duke Energy Carolinas [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	9	5
Gross Unrealized Holding Losses	2	6
Estimated Fair Value	407	354
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	1	2
Estimated Fair Value	60	67
Duke Energy Carolinas [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	3	5
Estimated Fair Value	417	458
Duke Energy Carolinas [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	3
Estimated Fair Value	132	116
Duke Energy Carolinas [Member] | Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses		1
Estimated Fair Value		3
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,095	952
Gross Unrealized Holding Losses	20	39
Estimated Fair Value	3,161	2,991
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,092	950
Gross Unrealized Holding Losses	20	39
Estimated Fair Value	3,102	2,926
Progress Energy [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	83	93
Progress Energy [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,074	935
Gross Unrealized Holding Losses	15	26
Estimated Fair Value	1,981	1,861
Progress Energy [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	6	5
Gross Unrealized Holding Losses		2
Estimated Fair Value	204	174
Progress Energy [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Gross Unrealized Holding Losses	2	8
Estimated Fair Value	280	264
Progress Energy [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	9	8
Gross Unrealized Holding Losses	3	3
Estimated Fair Value	544	526
Progress Energy [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	10	8
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Estimated Fair Value	59	65
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	12	21
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Estimated Fair Value	47	44
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	830	715
Gross Unrealized Holding Losses	16	32
Estimated Fair Value	2,380	2,214
Duke Energy Progress [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	830	715
Gross Unrealized Holding Losses	16	32
Estimated Fair Value	2,379	2,213
Duke Energy Progress [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	31	45
Duke Energy Progress [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	816	704
Gross Unrealized Holding Losses	12	21
Estimated Fair Value	1,607	1,505
Duke Energy Progress [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		1
Estimated Fair Value	142	120
Duke Energy Progress [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Gross Unrealized Holding Losses	2	8
Estimated Fair Value	279	263
Duke Energy Progress [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	6	5
Gross Unrealized Holding Losses	2	2
Estimated Fair Value	314	275
Duke Energy Progress [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	6	5
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	265	237
Gross Unrealized Holding Losses	4	7
Estimated Fair Value	771	761
Duke Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	262	235
Gross Unrealized Holding Losses	4	7
Estimated Fair Value	723	713
Duke Energy Florida [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	52	48
Duke Energy Florida [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	258	231
Gross Unrealized Holding Losses	3	5
Estimated Fair Value	374	356
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
Estimated Fair Value	62	54
Duke Energy Florida [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	1
Duke Energy Florida [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	3
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	230	251
Duke Energy Florida [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	4	3
Duke Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Estimated Fair Value	48	48
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	4
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Estimated Fair Value	47	44
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	40	33
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	118	110
Duke Energy Indiana [Member] | Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	40	33
Estimated Fair Value	87	79
Duke Energy Indiana [Member] | Other Classification [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	3	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	28
Duke Energy Indiana [Member] | Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	$ 1	$ 1