Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Regulatory assets	$ 1,031	$ 1,023
Current Assets: Other	425	458
Other Noncurrent Assets: Regulatory assets	12,838	12,878
Property, plant and equipment, cost	123,301	121,397
Accumulated depreciation and amortization	(40,293)	(39,406)
Current Liabilities: Other	1,570	2,044
Current maturities of long-term debt	1,977	2,319
Long-Term Debt	47,021	45,576
Deferred income taxes	14,443	14,155
Noncurrent Liabilities: Other	1,707	1,753
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Regulatory assets	233	238
Current Assets: Other	65	37
Other Noncurrent Assets: Regulatory assets	3,098	3,159
Property, plant and equipment, cost	41,600	41,127
Accumulated depreciation and amortization	(14,649)	(14,365)
Current Liabilities: Other	345	468
Current maturities of long-term debt	404	116
Long-Term Debt	8,787	9,187
Deferred income taxes	6,668	6,544
Noncurrent Liabilities: Other	595	607
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Regulatory assets	187	188
Current Assets: Other	102	57
Other Noncurrent Assets: Regulatory assets	3,338	3,243
Property, plant and equipment, cost	28,769	28,419
Accumulated depreciation and amortization	(10,716)	(10,561)
Current Liabilities: Other	294	365
Current maturities of long-term debt	202	452
Long-Term Debt	6,409	6,409
Deferred income taxes	3,453	3,323
Noncurrent Liabilities: Other	49	51
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Regulatory assets	260	213
Current Assets: Other	104	125
Other Noncurrent Assets: Regulatory assets	2,476	2,480
Property, plant and equipment, cost	17,122	16,434
Accumulated depreciation and amortization	(4,894)	(4,644)
Current Liabilities: Other	309	352
Current maturities of long-term debt	319	326
Long-Term Debt	6,662	5,799
Deferred income taxes	2,800	2,694
Noncurrent Liabilities: Other	104	105
DEFPF [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Receivables of VIEs	4	6
Current Assets: Regulatory assets	53	50
Current Assets: Other	14	53
Other Noncurrent Assets: Regulatory assets	1,131	1,142
Current Liabilities: Other	3	17
Current maturities of long-term debt	55	62
Long-Term Debt	1,189	1,217
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	425	425
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	300	300
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	225	225
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	325	325
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Other	336	223
Property, plant and equipment, cost	3,671	3,419
Accumulated depreciation and amortization	(448)	(453)
Current maturities of long-term debt	227	198
Long-Term Debt	1,645	1,097
Deferred income taxes	321	275
Noncurrent Liabilities: Other	$ 251	$ 252