Fair Value Measurements (Fair Value Measurement Amounts for Assets and Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	$ 108	$ 26
Total assets	6,506	6,240
Derivative liabilities	(428)	(419)
Net assets	6,078	5,821
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2
Total assets	4,584	4,260
Derivative liabilities	(1)
Net assets	4,583	4,260
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	72	16
Total assets	1,717	1,793
Derivative liabilities	(427)	(419)
Net assets	1,290	1,374
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	34	10
Total assets	38	15
Net assets	38	15
Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	167	172
Net assets	167	172
Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3,834	3,590
Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3,666	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	167	172
Equity Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	98	95
Equity Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	98	95
Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,158	2,227
Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	744	672
Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,414	1,555
Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	308	302
Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	74	75
Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	230	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	18
Total assets	3,184	3,041
Derivative liabilities	(89)	(45)
Net assets	3,095	2,996
Duke Energy Carolinas [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	2,205	2,168
Net assets	2,205	2,168
Duke Energy Carolinas [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	18
Total assets	809	698
Derivative liabilities	(89)	(45)
Net assets	720	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	167	172
Net assets	167	172
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,128	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	1,960	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	167	172
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,035	944
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	245	246
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	790	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	54	11
Total assets	2,951	2,853
Derivative liabilities	(100)	(322)
Net assets	2,851	2,531
Progress Energy [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	2,226	1,940
Net assets	2,226	1,940
Progress Energy [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	54	11
Total assets	725	913
Derivative liabilities	(100)	(322)
Net assets	625	591
Progress Energy [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,706	1,496
Progress Energy [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,706	1,496
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,123	1,283
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	499	426
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	624	857
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	68	63
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	21	18
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	47	45
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	25	2
Total assets	2,132	2,041
Derivative liabilities	(18)	(98)
Net assets	2,114	1,943
Duke Energy Progress [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	1,608	1,320
Net assets	1,608	1,320
Duke Energy Progress [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	25	2
Total assets	524	721
Derivative liabilities	(18)	(98)
Net assets	506	623
Duke Energy Progress [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,379	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	1,379	1,178
Duke Energy Progress [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	727	860
Duke Energy Progress [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	228	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	29	7
Total assets	803	799
Derivative liabilities	(76)	(216)
Net assets	727	583
Duke Energy Florida [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	602	609
Net assets	602	609
Duke Energy Florida [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	29	7
Total assets	201	190
Derivative liabilities	(76)	(216)
Net assets	125	(26)
Duke Energy Florida [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	327	318
Duke Energy Florida [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	327	318
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	396	423
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	271	285
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	125	138
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	51	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	4	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	47	45
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	5	3
Derivative liabilities	(8)	(7)
Net assets	(3)	(4)
Duke Energy Ohio [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(8)	(7)
Net assets	(8)	(7)
Duke Energy Ohio [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	5	3
Net assets	5	3
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	31	7
Total assets	135
Derivative liabilities	1
Net assets	134	108
Duke Energy Indiana [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2
Total assets	75
Derivative liabilities	1
Net assets	74	73
Duke Energy Indiana [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	31
Net assets	31	28
Duke Energy Indiana [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	29	7
Total assets	29
Net assets	29	7
Duke Energy Indiana [Member] | Equity Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	73	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	73	71
Duke Energy Indiana [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	31	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		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	$ 31	$ 28