Fair Value Measurements (Fair Value Measurement Amounts for Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	$ 26	$ 110
Assets, fair value disclosure	6,240	6,018
Derivative liabilities	(419)	(668)
Net assets, fair value	5,821	5,350
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	49
Assets, fair value disclosure	4,260	4,327
Derivative liabilities	0	(162)
Net assets, fair value	4,260	4,165
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	16	24
Assets, fair value disclosure	1,793	1,498
Derivative liabilities	(419)	(468)
Net assets, fair value	1,374	1,030
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	10	37
Assets, fair value disclosure	15	42
Derivative liabilities	0	(38)
Net assets, fair value	15	4
Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	172	151
Net assets, fair value	172	151
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	3,041	3,035
Derivative liabilities	(45)	(19)
Net assets, fair value	2,996	3,016
Duke Energy Carolinas [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	2,168	2,143
Net assets, fair value	2,168	2,143
Duke Energy Carolinas [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	698	738
Derivative liabilities	(45)	(19)
Net assets, fair value	653	719
Duke Energy Carolinas [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	3	3
Net assets, fair value	3	3
Duke Energy Carolinas [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	172	151
Net assets, fair value	172	151
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	11	4
Assets, fair value disclosure	2,853	2,579
Derivative liabilities	(322)	(373)
Net assets, fair value	2,531	2,206
Progress Energy [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	1,940	2,013
Net assets, fair value	1,940	2,013
Progress Energy [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	11	4
Assets, fair value disclosure	913	566
Derivative liabilities	(322)	(373)
Net assets, fair value	591	193
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2
Assets, fair value disclosure	2,041	1,711
Derivative liabilities	(98)	(132)
Net assets, fair value	1,943	1,579
Duke Energy Progress [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	1,320	1,322
Net assets, fair value	1,320	1,322
Duke Energy Progress [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2
Assets, fair value disclosure	721	389
Derivative liabilities	(98)	(132)
Net assets, fair value	623	257
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	4
Assets, fair value disclosure	799	854
Derivative liabilities	(216)	(241)
Net assets, fair value	583	613
Duke Energy Florida [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	609	676
Net assets, fair value	609	676
Duke Energy Florida [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	4
Assets, fair value disclosure	190	178
Derivative liabilities	(216)	(241)
Net assets, fair value	(26)	(63)
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	49
Derivative liabilities	(7)	(181)
Net assets, fair value	(4)	(132)
Duke Energy Ohio [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets		20
Derivative liabilities	0	(117)
Net assets, fair value		(97)
Duke Energy Ohio [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets		9
Derivative liabilities	(7)	(26)
Net assets, fair value	(7)	(17)
Duke Energy Ohio [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	20
Derivative liabilities		(38)
Net assets, fair value	3	(18)
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	14
Net assets, fair value	108	115
Duke Energy Indiana [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0
Net assets, fair value	73	71
Duke Energy Indiana [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net assets, fair value	28	30
Duke Energy Indiana [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	14
Net assets, fair value	7	14
NDTF [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3,590	3,650
NDTF [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3,418	3,493
NDTF [Member] | Equity Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		6
NDTF [Member] | Equity Securities [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	172	151
NDTF [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,227	1,899
NDTF [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	672	648
NDTF [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,555	1,251
NDTF [Member] | Duke Energy Carolinas [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,094	2,162
NDTF [Member] | Duke Energy Carolinas [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,922	2,005
NDTF [Member] | Duke Energy Carolinas [Member] | Equity Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		6
NDTF [Member] | Duke Energy Carolinas [Member] | Equity Securities [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	172	151
NDTF [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	944	870
NDTF [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	246	138
NDTF [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	698	732
NDTF [Member] | Progress Energy [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,496	1,488
NDTF [Member] | Progress Energy [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,496	1,488
NDTF [Member] | Progress Energy [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,283	1,029
NDTF [Member] | Progress Energy [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	426	510
NDTF [Member] | Progress Energy [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	857	519
NDTF [Member] | Duke Energy Progress [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,178	1,171
NDTF [Member] | Duke Energy Progress [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,178	1,171
NDTF [Member] | Duke Energy Progress [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	860	540
NDTF [Member] | Duke Energy Progress [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	141	151
NDTF [Member] | Duke Energy Progress [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	719	389
NDTF [Member] | Duke Energy Florida [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	318	317
NDTF [Member] | Duke Energy Florida [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	318	317
NDTF [Member] | Duke Energy Florida [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	423	489
NDTF [Member] | Duke Energy Florida [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	285	359
NDTF [Member] | Duke Energy Florida [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	138	130
Other Classification [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	95	96
Other Classification [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	95	96
Other Classification [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	302	263
Other Classification [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	75	41
Other Classification [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	222	217
Other Classification [Member] | Debt Securities [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	5	5
Other Classification [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3	3
Other Classification [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3	3
Other Classification [Member] | Progress Energy [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	63	58
Other Classification [Member] | Progress Energy [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	18	15
Other Classification [Member] | Progress Energy [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	45	43
Other Classification [Member] | Duke Energy Progress [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1
Other Classification [Member] | Duke Energy Progress [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1
Other Classification [Member] | Duke Energy Florida [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	51	44
Other Classification [Member] | Duke Energy Florida [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	6
Other Classification [Member] | Duke Energy Florida [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	45	44
Other Classification [Member] | Duke Energy Indiana [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, equity securities	71	71
Other Classification [Member] | Duke Energy Indiana [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, equity securities	71	71
Other Classification [Member] | Duke Energy Indiana [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, debt securities	30	30
Other Classification [Member] | Duke Energy Indiana [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, debt securities	2
Other Classification [Member] | Duke Energy Indiana [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, debt securities	$ 28	$ 30