Variable Interest Entities (Consolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	$ 1,973	$ 1,719
Other current assets	1,837	1,821
Investments and other assets	3,008	3,432
Total property, plant and equipment	104,861	103,115
Accumulated depreciation and amortization	(34,824)	(33,625)
Other deferred debits	171	181
Accounts payable	2,271	2,391
Current maturities of long-term debt	2,807	2,104
Other current liabilities	2,188	1,996
Long-Term debt	37,213	38,152
Deferred income taxes	13,423	12,097
Asset retirement obligations	8,466	4,950
Other liabilities	1,675	1,749
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	1,973	1,719
Other current assets	74	101
Investments and other assets	50	80
Total property, plant and equipment	1,873	1,680
Accumulated depreciation and amortization	(255)	(175)
Other deferred debits	36	36
Total assets	3,751	3,441
Accounts payable	3	2
Taxes accrued	6	10
Current maturities of long-term debt	84	80
Other current liabilities	21	27
Long-Term debt	2,234	1,966
Deferred income taxes	283	290
Asset retirement obligations	29	26
Other liabilities	38	31
Total liabilities	2,698	2,432
Net assets of consolidated VIEs	1,053	1,009
Duke Energy Carolinas [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	647	673
Other current assets	77	309
Investments and other assets	959	1,000
Total property, plant and equipment	37,372	34,906
Accumulated depreciation and amortization	(12,700)	(11,894)
Other deferred debits	42	46
Accounts payable	709	701
Current maturities of long-term debt	507	47
Other current liabilities	434	393
Long-Term debt	7,584	8,089
Deferred income taxes	5,812	5,706
Asset retirement obligations	3,428	1,594
Other liabilities	642	676
Duke Energy Progress [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	436	417
Other current assets	384	296
Investments and other assets	412	443
Total property, plant and equipment	24,207	22,273
Accumulated depreciation and amortization	(9,021)	(8,623)
Other deferred debits	34	32
Accounts payable	481	420
Current maturities of long-term debt	945	174
Other current liabilities	409	392
Long-Term debt	5,256	5,061
Deferred income taxes	2,908	2,557
Asset retirement obligations	3,905	1,729
Other liabilities	168	222
Duke Energy Florida [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	305
Other current assets	521	182
Investments and other assets	204	252
Total property, plant and equipment	14,433	13,863
Accumulated depreciation and amortization	(4,478)	(4,252)
Other deferred debits	39	44
Accounts payable	365	333
Current maturities of long-term debt	562	11
Other current liabilities	586	445
Long-Term debt	4,298	4,875
Deferred income taxes	2,452	1,829
Asset retirement obligations	806	833
Other liabilities	158	255
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 variable interest entities (net of allowance for doubtful accounts)	647	673
Other deferred debits		1
Total assets	647	674
Long-Term debt	400	400
Other liabilities		1
Total liabilities	400	401
Net assets of consolidated VIEs	247	273
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 variable interest entities (net of allowance for doubtful accounts)	436	416
Other deferred debits		1
Total assets	436	417
Long-Term debt	300	300
Total liabilities	300	300
Net assets of consolidated VIEs	136	117
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 variable interest entities (net of allowance for doubtful accounts)	305
Total assets	305
Long-Term debt	225
Total liabilities	225
Net assets of consolidated VIEs	80
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	547	595
Total assets	547	595
Long-Term debt	325	325
Total liabilities	325	325
Net assets of consolidated VIEs	222	270
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	20	18
Other current assets	68	89
Investments and other assets	25	29
Total property, plant and equipment	1,855	1,662
Accumulated depreciation and amortization	(250)	(170)
Other deferred debits	34	34
Total assets	1,752	1,662
Accounts payable	3	2
Taxes accrued	6	10
Current maturities of long-term debt	68	66
Other current liabilities	16	17
Long-Term debt	967	907
Deferred income taxes	283	290
Asset retirement obligations	29	26
Other liabilities	34	17
Total liabilities	1,406	1,335
Net assets of consolidated VIEs	346	327
Other VIEs [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	18	17
Other current assets	6	12
Investments and other assets	25	51
Total property, plant and equipment	18	18
Accumulated depreciation and amortization	(5)	(5)
Other deferred debits	2
Total assets	64	93
Current maturities of long-term debt	16	14
Other current liabilities	5	10
Long-Term debt	17	34
Other liabilities	4	13
Total liabilities	42	71
Net assets of consolidated VIEs	$ 22	$ 22