Variable Interest Entities (Schedule of Consolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	$ 2,016	$ 1,973
Other current assets	2,008	1,837
Investments and other assets	3,207	3,008
Property, plant and equipment, cost	105,692	104,861
Accumulated depreciation and amortization	(35,400)	(34,824)
Other deferred debits	182	171
Accounts payable	1,920	2,271
Current maturities of long-term debt	2,800	2,807
Other current liabilities	2,014	2,188
Long-Term Debt	37,173	37,213
Deferred income taxes	13,914	13,423
Asset retirement obligation	8,541	8,466
Other liabilities	1,667	1,675
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	2,016	1,973
Other current assets	109	74
Investments and other assets	37	50
Property, plant and equipment, cost	1,873	1,873
Accumulated depreciation and amortization	(273)	(255)
Other deferred debits	38	36
Total assets	3,800	3,751
Accounts payable	2	3
Taxes accrued	9	6
Current maturities of long-term debt	85	84
Other current liabilities	31	21
Long-Term Debt	2,229	2,234
Deferred income taxes	270	283
Asset retirement obligation	30	29
Other liabilities	40	38
Total liabilities	2,696	2,698
Net assets of consolidated VIEs	1,104	1,053
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	658	647
Other current assets	41	77
Investments and other assets	996	959
Property, plant and equipment, cost	37,682	37,372
Accumulated depreciation and amortization	(12,935)	(12,700)
Other deferred debits	45	42
Accounts payable	504	709
Current maturities of long-term debt	506	507
Other current liabilities	398	434
Long-Term Debt	8,079	7,584
Deferred income taxes	5,901	5,812
Asset retirement obligation	3,460	3,428
Other liabilities	640	642
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	479	436
Other current assets	99	384
Investments and other assets	450	412
Property, plant and equipment, cost	24,444	24,207
Accumulated depreciation and amortization	(9,162)	(9,021)
Other deferred debits	34	34
Accounts payable	363	481
Current maturities of long-term debt	702	945
Other current liabilities	359	409
Long-Term Debt	5,255	5,256
Deferred income taxes	2,978	2,908
Asset retirement obligation	3,936	3,905
Other liabilities	175	168
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	301	305
Other current assets	333	521
Investments and other assets	270	204
Property, plant and equipment, cost	14,613	14,433
Accumulated depreciation and amortization	(4,545)	(4,478)
Other deferred debits	39	39
Accounts payable	302	365
Current maturities of long-term debt	562	562
Other current liabilities	577	586
Long-Term Debt	4,296	4,298
Deferred income taxes	2,465	2,452
Asset retirement obligation	803	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	658	647
Total assets	658	647
Taxes accrued	2
Long-Term Debt	400	400
Total liabilities	402	400
Net assets of consolidated VIEs	256	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	478	436
Other deferred debits	1
Total assets	479	436
Taxes accrued	2
Long-Term Debt	300	300
Total liabilities	302	300
Net assets of consolidated VIEs	177	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	300	305
Other deferred debits	1
Total assets	301	305
Taxes accrued	1
Long-Term Debt	225	225
Total liabilities	226	225
Net assets of consolidated VIEs	75	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	540	547
Total assets	540	547
Long-Term Debt	325	325
Total liabilities	325	325
Net assets of consolidated VIEs	215	222
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	18	20
Other current assets	102	68
Investments and other assets	22	25
Property, plant and equipment, cost	1,854	1,855
Accumulated depreciation and amortization	(267)	(250)
Other deferred debits	36	34
Total assets	1,765	1,752
Accounts payable	2	3
Taxes accrued	4	6
Current maturities of long-term debt	68	68
Other current liabilities	23	16
Long-Term Debt	967	967
Deferred income taxes	270	283
Asset retirement obligation	30	29
Other liabilities	40	34
Total liabilities	1,404	1,406
Net assets of consolidated VIEs	361	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	7	6
Investments and other assets	15	25
Property, plant and equipment, cost	19	18
Accumulated depreciation and amortization	(6)	(5)
Other deferred debits		2
Total assets	57	64
Current maturities of long-term debt	17	16
Other current liabilities	8	5
Long-Term Debt	12	17
Other liabilities		4
Total liabilities	37	42
Net assets of consolidated VIEs	$ 20	$ 22