Fair Value Measurements (Fair Value Measurement Amounts for Assets and Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	$ 33	$ 26
Total assets	6,331	6,240
Derivative liabilities	(537)	(419)
Net assets	5,794	5,821
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0
Total assets	4,543	4,260
Derivative liabilities	(6)
Net assets	4,537	4,260
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	31	16
Total assets	1,617	1,793
Derivative liabilities	(531)	(419)
Net assets	1,086	1,374
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2	10
Total assets	6	15
Net assets	6	15
Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	165	172
Net assets	165	172
Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3,592	3,590
Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3,426	3,418
Equity Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1
Equity Securities [Member] | Ndtf [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	165	172
Equity Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	97	95
Equity Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	97	95
Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,302	2,227
Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	935	672
Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,367	1,555
Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	307	302
Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	85	75
Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	218	222
Debt Securities [Member] | Other Classification [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	4	5
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	13
Total assets	3,104	3,041
Derivative liabilities	(81)	(45)
Net assets	3,023	2,996
Duke Energy Carolinas [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	2,186	2,168
Net assets	2,186	2,168
Duke Energy Carolinas [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	13
Total assets	750	698
Derivative liabilities	(81)	(45)
Net assets	669	653
Duke Energy Carolinas [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	3	3
Net assets	3	3
Duke Energy Carolinas [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	165	172
Net assets	165	172
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,088	2,094
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,922	1,922
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	165	172
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,000	944
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	264	246
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	736	698
Duke Energy Carolinas [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3	3
Duke Energy Carolinas [Member] | Debt Securities [Member] | Other Classification [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3	3
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	17	11
Total assets	2,886	2,853
Derivative liabilities	(298)	(322)
Net assets	2,588	2,531
Progress Energy [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	2,192	1,940
Derivative liabilities	0
Net assets	2,192	1,940
Progress Energy [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	17	11
Total assets	694	913
Derivative liabilities	(298)	(322)
Net assets	396	591
Progress Energy [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,504	1,496
Progress Energy [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,504	1,496
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,302	1,283
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	671	426
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	631	857
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	63	63
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	17	18
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	46	45
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	5	2
Total assets	2,078	2,041
Derivative liabilities	(87)	(98)
Net assets	1,991	1,943
Duke Energy Progress [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	1,574	1,320
Net assets	1,574	1,320
Duke Energy Progress [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	5	2
Total assets	504	721
Derivative liabilities	(87)	(98)
Net assets	417	623
Duke Energy Progress [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,184	1,178
Duke Energy Progress [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,184	1,178
Duke Energy Progress [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	888	860
Duke Energy Progress [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	389	141
Duke Energy Progress [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	499	719
Duke Energy Progress [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1	1
Duke Energy Progress [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1	1
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	11	7
Total assets	792	799
Derivative liabilities	(206)	(216)
Net assets	586	583
Duke Energy Florida [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	603	609
Net assets	603	609
Duke Energy Florida [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	11	7
Total assets	189	190
Derivative liabilities	(206)	(216)
Net assets	(17)	(26)
Duke Energy Florida [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	320	318
Duke Energy Florida [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	320	318
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	414	423
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	282	285
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	132	138
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	47	51
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1	6
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	46	45
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets		3
Derivative liabilities	(7)	(7)
Net assets	(7)	(4)
Duke Energy Ohio [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	0
Duke Energy Ohio [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(7)	(7)
Net assets	(7)	(7)
Duke Energy Ohio [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets		3
Net assets		3
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2	7
Net assets	104	108
Duke Energy Indiana [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net assets	73	73
Duke Energy Indiana [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net assets	29	28
Duke Energy Indiana [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2	7
Net assets	2	7
Duke Energy Indiana [Member] | Equity Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	72	71
Duke Energy Indiana [Member] | Equity Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	72	71
Duke Energy Indiana [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	30	30
Duke Energy Indiana [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1	2
Duke Energy Indiana [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 29	$ 28