Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	$ 2,046	$ 1,973
Other current assets	1,498	1,837
Investments and other assets	3,239	3,008
Property, plant and equipment, cost	107,125	104,861
Accumulated depreciation and amortization	(35,826)	(34,824)
Other deferred debits	183	171
Accounts payable	1,920	2,271
Current maturities of long-term debt	2,374	2,807
Other current liabilities	1,976	2,188
Long-Term Debt	36,795	37,213
Deferred income taxes	13,664	13,423
Asset retirement obligation	9,490	8,466
Other liabilities	1,588	1,675
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	2,046	1,973
Other current assets	92	74
Investments and other assets	35	50
Property, plant and equipment, cost	1,876	1,873
Accumulated depreciation and amortization	(291)	(255)
Other deferred debits	39	36
Total assets	3,797	3,751
Accounts payable	2	3
Taxes accrued	10	6
Current maturities of long-term debt	91	84
Other current liabilities	20	21
Long-Term Debt	2,163	2,234
Deferred income taxes	264	283
Asset retirement obligation	30	29
Other liabilities	32	38
Total liabilities	2,612	2,698
Net assets of consolidated VIEs	1,185	1,053
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	692	647
Other current assets	54	77
Investments and other assets	1,041	959
Property, plant and equipment, cost	38,085	37,372
Accumulated depreciation and amortization	(13,120)	(12,700)
Other deferred debits	44	42
Accounts payable	494	709
Current maturities of long-term debt	506	507
Other current liabilities	379	434
Long-Term Debt	8,079	7,584
Deferred income taxes	6,019	5,812
Asset retirement obligation	3,604	3,428
Other liabilities	617	642
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	469	436
Other current assets	49	384
Investments and other assets	464	412
Property, plant and equipment, cost	24,093	24,207
Accumulated depreciation and amortization	(8,982)	(9,021)
Other deferred debits	33	34
Accounts payable	342	481
Current maturities of long-term debt	402	945
Other current liabilities	349	409
Long-Term Debt	5,255	5,256
Deferred income taxes	3,012	2,908
Asset retirement obligation	4,262	3,905
Other liabilities	167	168
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	385	305
Other current assets	282	521
Investments and other assets	283	204
Property, plant and equipment, cost	14,854	14,433
Accumulated depreciation and amortization	(4,625)	(4,478)
Other deferred debits	37	39
Accounts payable	346	365
Current maturities of long-term debt	562	562
Other current liabilities	543	586
Long-Term Debt	4,293	4,298
Deferred income taxes	2,500	2,452
Asset retirement obligation	733	806
Other liabilities	146	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	692	647
Other deferred debits	1
Total assets	693	647
Taxes accrued	3
Long-Term Debt	400	400
Total liabilities	403	400
Net assets of consolidated VIEs	290	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	469	436
Other deferred debits	1
Total assets	470	436
Taxes accrued	2
Long-Term Debt	300	300
Total liabilities	302	300
Net assets of consolidated VIEs	168	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	385	305
Other current assets	1
Other deferred debits	1
Total assets	387	305
Taxes accrued	1
Long-Term Debt	225	225
Total liabilities	226	225
Net assets of consolidated VIEs	161	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	467	547
Total assets	467	547
Long-Term Debt	314	325
Total liabilities	314	325
Net assets of consolidated VIEs	153	222
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	13	20
Other current assets	83	68
Investments and other assets	24	25
Property, plant and equipment, cost	1,856	1,855
Accumulated depreciation and amortization	(285)	(250)
Other deferred debits	38	34
Total assets	1,729	1,752
Accounts payable	2	3
Taxes accrued	4	6
Current maturities of long-term debt	73	68
Other current liabilities	14	16
Long-Term Debt	917	967
Deferred income taxes	264	283
Asset retirement obligation	30	29
Other liabilities	31	34
Total liabilities	1,335	1,406
Net assets of consolidated VIEs	394	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	20	18
Other current assets	8	6
Investments and other assets	11	25
Property, plant and equipment, cost	20	18
Accumulated depreciation and amortization	(6)	(5)
Other deferred debits	(2)	2
Total assets	51	64
Current maturities of long-term debt	18	16
Other current liabilities	6	5
Long-Term Debt	7	17
Other liabilities	1	4
Total liabilities	32	42
Net assets of consolidated VIEs	$ 19	$ 22