Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 1,370	$ 2,036	$ 1,931	$ 1,501
Restricted receivables of VIEs	2,037	1,973
Other current assets	1,566	1,837
Investments and other assets	3,205	3,008
Property, plant and equipment, cost	110,795	104,861
Accumulated depreciation and amortization	(37,479)	(34,824)
Other deferred debits	188	171
Accounts payable	2,078	2,271
Current maturities of long-term debt	2,536	2,807
Other current liabilities	2,052	2,188
Long-Term Debt	37,667	37,213
Deferred income taxes	13,999	13,423
Asset retirement obligation	9,713	8,466
Other liabilities	1,595	1,675
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	2
Restricted receivables of VIEs	2,037	1,973
Other current assets	222	74
Investments and other assets	25	50
Property, plant and equipment, cost	1,945	1,873
Accumulated depreciation and amortization	(307)	(255)
Other deferred debits	38	36
Total assets	3,962	3,751
Accounts payable	6	3
Taxes accrued	15	6
Current maturities of long-term debt	91	84
Other current liabilities	27	21
Long-Term Debt	2,169	2,234
Deferred income taxes	325	283
Asset retirement obligation	30	29
Other liabilities	42	38
Total liabilities	2,705	2,698
Net assets of consolidated VIEs	1,257	1,053
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	198	13	34	23
Restricted receivables of VIEs	687	647
Other current assets	164	77
Investments and other assets	1,018	959
Property, plant and equipment, cost	38,653	37,372
Accumulated depreciation and amortization	(13,445)	(12,700)
Other deferred debits	43	42
Accounts payable	623	709
Current maturities of long-term debt	506	507
Other current liabilities	415	434
Long-Term Debt	8,078	7,584
Deferred income taxes	6,067	5,812
Asset retirement obligation	3,599	3,428
Other liabilities	618	642
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	123	9	6	21
Restricted receivables of VIEs	468	436
Other current assets	53	384
Investments and other assets	484	412
Property, plant and equipment, cost	26,919	24,207
Accumulated depreciation and amortization	(10,207)	(9,021)
Other deferred debits	40	34
Accounts payable	381	481
Current maturities of long-term debt	402	945
Other current liabilities	375	409
Long-Term Debt	6,449	5,256
Deferred income taxes	3,097	2,908
Asset retirement obligation	4,489	3,905
Other liabilities	120	168
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	16	8	$ 15	$ 16
Restricted receivables of VIEs	395	305
Other current assets	179	521
Investments and other assets	308	204
Property, plant and equipment, cost	15,011	14,433
Accumulated depreciation and amortization	(4,648)	(4,478)
Other deferred debits	36	39
Accounts payable	316	365
Current maturities of long-term debt	563	562
Other current liabilities	553	586
Long-Term Debt	4,287	4,298
Deferred income taxes	2,579	2,452
Asset retirement obligation	732	806
Other liabilities	157	158
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	687	647
Total assets	687	647
Taxes accrued	5
Long-Term Debt	400	400
Total liabilities	405	400
Net assets of consolidated VIEs	282	247
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	468	436
Other current assets	1
Total assets	469	436
Taxes accrued	3
Long-Term Debt	300	300
Total liabilities	303	300
Net assets of consolidated VIEs	166	136
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	395	305
Other current assets	2
Total assets	397	305
Taxes accrued	1
Long-Term Debt	225	225
Total liabilities	226	225
Net assets of consolidated VIEs	171	80
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	453	547
Total assets	453	547
Long-Term Debt	325	325
Total liabilities	325	325
Net assets of consolidated VIEs	128	222
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	2
Restricted receivables of VIEs	12	20
Other current assets	215	68
Investments and other assets	20	25
Property, plant and equipment, cost	1,926	1,855
Accumulated depreciation and amortization	(302)	(250)
Other deferred debits	37	34
Total assets	1,910	1,752
Accounts payable	6	3
Taxes accrued	6	6
Current maturities of long-term debt	73	68
Other current liabilities	23	16
Long-Term Debt	916	967
Deferred income taxes	325	283
Asset retirement obligation	30	29
Other liabilities	42	34
Total liabilities	1,421	1,406
Net assets of consolidated VIEs	489	346
Other VIEs [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	22	18
Other current assets	4	6
Investments and other assets	5	25
Property, plant and equipment, cost	19	18
Accumulated depreciation and amortization	(5)	(5)
Other deferred debits	1	2
Total assets	46	64
Current maturities of long-term debt	18	16
Other current liabilities	4	5
Long-Term Debt	3	17
Other liabilities		4
Total liabilities	25	42
Net assets of consolidated VIEs	$ 21	$ 22