Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	$ 1,192	$ 1,023
Other, current assets	436	458
Regulatory assets, noncurrent	12,808	12,878
Property, plant and equipment, cost	124,439	121,397
Accumulated depreciation and amortization	(40,522)	(39,406)
Current Liabilities: Other	1,708	2,044
Current maturities of long-term debt	3,472	2,319
Long-Term Debt	46,043	45,576
Deferred income taxes	14,695	14,155
Noncurrent Liabilities: Other	1,651	1,753
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	249	238
Other, current assets	34	37
Regulatory assets, noncurrent	3,060	3,159
Property, plant and equipment, cost	41,881	41,127
Accumulated depreciation and amortization	(14,632)	(14,365)
Current Liabilities: Other	409	468
Current maturities of long-term debt	704	116
Long-Term Debt	8,520	9,187
Deferred income taxes	6,742	6,544
Noncurrent Liabilities: Other	574	607
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	212	188
Other, current assets	76	57
Regulatory assets, noncurrent	3,379	3,243
Property, plant and equipment, cost	28,936	28,419
Accumulated depreciation and amortization	(10,734)	(10,561)
Current Liabilities: Other	308	365
Current maturities of long-term debt	203	452
Long-Term Debt	6,407	6,409
Deferred income taxes	3,539	3,323
Noncurrent Liabilities: Other	47	51
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory assets, current	321	213
Other, current assets	50	125
Regulatory assets, noncurrent	2,474	2,480
Property, plant and equipment, cost	17,369	16,434
Accumulated depreciation and amortization	(4,910)	(4,644)
Current Liabilities: Other	322	352
Current maturities of long-term debt	819	326
Long-Term Debt	6,160	5,799
Deferred income taxes	2,893	2,694
Noncurrent Liabilities: Other	103	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	5	6
Regulatory assets, current	52	50
Other, current assets	33	53
Regulatory assets, noncurrent	1,121	1,142
Current Liabilities: Other	10	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	297	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]
Other, current assets	293	223
Property, plant and equipment, cost	3,695	3,419
Accumulated depreciation and amortization	(518)	(453)
Current maturities of long-term debt	157	198
Long-Term Debt	1,557	1,097
Deferred income taxes	300	275
Noncurrent Liabilities: Other	$ 249	$ 252