Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 778	$ 857	$ 2,821	$ 2,036
Restricted receivables of VIEs	1,714	1,748
Other current assets	308	327
Investments and other assets	3,036	3,042
Property, plant and equipment, cost	113,942	112,826
Accumulated depreciation and amortization	(38,154)	(37,665)
Other deferred debits	39	43
Accounts payable	2,086	2,400
Current maturities of long-term debt	2,075	2,074
Other current liabilities	1,965	2,115
Long-Term Debt	38,232	37,495
Deferred income taxes	12,825	12,705
Asset retirement obligation	10,269	10,264
Other liabilities	1,703	1,706
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	2
Restricted receivables of VIEs	1,714	1,748
Other current assets	151	142
Investments and other assets	58	70
Property, plant and equipment, cost	2,047	2,035
Accumulated depreciation and amortization	(346)	(327)
Total assets	3,626	3,670
Accounts payable	23	35
Taxes accrued	4	14
Current maturities of long-term debt	94	125
Other current liabilities	22	17
Long-Term Debt	2,270	2,197
Deferred income taxes	240	289
Asset retirement obligation	37	35
Other liabilities	42	33
Total liabilities	2,732	2,745
Net assets of consolidated VIEs	894	925
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	17	13	30	13
Restricted receivables of VIEs	615	596
Other current assets	32	128
Investments and other assets	1,003	999
Property, plant and equipment, cost	39,833	39,398
Accumulated depreciation and amortization	(13,769)	(13,521)
Other deferred debits	4	4
Accounts payable	597	753
Current maturities of long-term debt	468	356
Other current liabilities	452	519
Long-Term Debt	8,592	7,711
Deferred income taxes	6,298	6,146
Asset retirement obligation	3,913	3,918
Other liabilities	642	621
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	11	15	6	9
Restricted receivables of VIEs	372	349
Other current assets	51	121
Investments and other assets	521	486
Property, plant and equipment, cost	27,503	27,313
Accumulated depreciation and amortization	(10,266)	(10,141)
Other deferred debits	2	3
Accounts payable	295	399
Current maturities of long-term debt	252	2
Other current liabilities	382	412
Long-Term Debt	6,163	6,366
Deferred income taxes	3,089	3,027
Asset retirement obligation	4,573	4,567
Other liabilities	29	45
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	12	8	$ 10	$ 8
Restricted receivables of VIEs	256	308
Other current assets	52	21
Investments and other assets	301	292
Property, plant and equipment, cost	15,652	15,343
Accumulated depreciation and amortization	(4,734)	(4,720)
Other deferred debits	2	2
Accounts payable	371	322
Current maturities of long-term debt	13	13
Other current liabilities	451	452
Long-Term Debt	4,252	4,253
Deferred income taxes	2,544	2,460
Asset retirement obligation	799	802
Other liabilities	132	146
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	615	596
Total assets	615	596
Taxes accrued		5
Long-Term Debt	425	425
Total liabilities	425	430
Net assets of consolidated VIEs	190	166
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	372	349
Total assets	372	349
Taxes accrued		3
Long-Term Debt	300	254
Total liabilities	300	257
Net assets of consolidated VIEs	72	92
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	256	309
Total assets	256	309
Long-Term Debt	225	225
Total liabilities	225	225
Net assets of consolidated VIEs	31	84
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	437	454
Total assets	437	454
Long-Term Debt	325	325
Total liabilities	325	325
Net assets of consolidated VIEs	112	129
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	20	19
Other current assets	149	138
Investments and other assets	58	70
Property, plant and equipment, cost	2,027	2,015
Accumulated depreciation and amortization	(340)	(321)
Total assets	1,914	1,921
Accounts payable	23	35
Taxes accrued	4	5
Current maturities of long-term debt	82	108
Other current liabilities	22	15
Long-Term Debt	995	968
Deferred income taxes	240	289
Asset retirement obligation	37	35
Other liabilities	42	33
Total liabilities	1,445	1,488
Net assets of consolidated VIEs	469	433
Other VIEs [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	2
Restricted receivables of VIEs	14	21
Other current assets	2	4
Property, plant and equipment, cost	20	20
Accumulated depreciation and amortization	(6)	(6)
Total assets	32	41
Taxes accrued		1
Current maturities of long-term debt	12	17
Other current liabilities		2
Total liabilities	12	20
Net assets of consolidated VIEs	$ 20	$ 21