Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current Assets [Abstract]
Cash and cash equivalents	$ 358	$ 392
Receivables (net of allowance for doubtful accounts)	779	751
Receivables of VIEs (net of allowance for doubtful accounts)	1,995	1,893
Inventory	3,250	3,522
Regulatory assets	1,437	1,023
Other	634	458
Total current assets	8,453	8,039
Property, Plant and Equipment [Abstract]
Cost	127,507	121,397
Accumulated depreciation and amortization	(41,537)	(39,406)
Generation facilities to be retired, net	421	529
Net property, plant and equipment	86,391	82,520
Other Noncurrent Assets
Goodwill	19,396	19,425
Regulatory assets	12,442	12,878
Nuclear decommissioning trust funds	7,097	6,205
Investments in equity method unconsolidated affiliates	1,175	925
Other	2,960	2,769
Total other noncurrent assets	43,070	42,202
Total Assets	137,914	132,761
Current Liabilities [Abstract]
Accounts payable	3,043	2,994
Notes payable and commercial paper	2,163	2,487
Taxes accrued	551	384
Interest accrued	525	503
Current maturities of long-term debt	3,244	2,319
Asset retirement obligations	689	411
Regulatory liabilities	402	409
Other	1,865	2,044
Total current liabilities	12,482	11,551
Long-Term Debt	49,035	45,576
Other Noncurrent Liabilities [Abstract]
Deferred income taxes	6,621	14,155
Asset retirement obligations	9,486	10,200
Regulatory liabilities	15,330	6,881
Accrued pension and other post-retirement benefit costs	1,103	1,111
Investment tax credits	539	493
Other	1,581	1,753
Total other noncurrent liabilities	34,660	34,593
Commitments and Contingencies
Equity [Abstract]
Common stock	1	1
Additional paid-in capital	38,792	38,741
Retained earnings	3,013	2,384
Accumulated other comprehensive (loss) income	(67)	(93)
Total Parent stockholders' equity	41,739	41,033
Noncontrolling interests	(2)	8
Total equity	41,737	41,041
Total Liabilities and Equity	137,914	132,761
Duke Energy Carolinas [Member]
Current Assets [Abstract]
Cash and cash equivalents	16	14
Receivables (net of allowance for doubtful accounts)	200	160
Receivables of VIEs (net of allowance for doubtful accounts)	640	645
Receivables from affiliated companies	95	163
Notes receivable from affiliated companies		66
Inventory	971	1,055
Regulatory assets	299	238
Other	19	37
Total current assets	2,240	2,378
Property, Plant and Equipment [Abstract]
Cost	42,939	41,127
Accumulated depreciation and amortization	(15,063)	(14,365)
Net property, plant and equipment	27,876	26,762
Other Noncurrent Assets
Regulatory assets	2,853	3,159
Nuclear decommissioning trust funds	3,772	3,273
Other	979	943
Total other noncurrent assets	7,604	7,375
Total Assets	37,720	36,515
Current Liabilities [Abstract]
Accounts payable	842	833
Accounts payable to affiliated companies	209	247
Notes payable to affiliated companies	104
Taxes accrued	234	143
Interest accrued	108	102
Current maturities of long-term debt	1,205	116
Asset retirement obligations	337	222
Regulatory liabilities	126	161
Other	486	468
Total current liabilities	3,651	2,292
Long-Term Debt	8,598	9,187
Long-Term Debt Payable to Affiliated Companies	300	300
Other Noncurrent Liabilities [Abstract]
Deferred income taxes	3,413	6,544
Asset retirement obligations	3,273	3,673
Regulatory liabilities	6,231	2,840
Accrued pension and other post-retirement benefit costs	95	97
Investment tax credits	232	203
Other	566	607
Total other noncurrent liabilities	13,810	13,964
Commitments and Contingencies
Equity [Abstract]
Member's equity	11,368	10,781
Accumulated other comprehensive (loss) income	(7)	(9)
Total member's equity	11,361	10,772
Total Liabilities and Equity	37,720	36,515
Progress Energy [Member]
Current Assets [Abstract]
Cash and cash equivalents	40	46
Receivables (net of allowance for doubtful accounts)	123	114
Receivables of VIEs (net of allowance for doubtful accounts)	780	692
Receivables from affiliated companies	31	106
Notes receivable from affiliated companies	240	80
Inventory	1,592	1,717
Regulatory assets	741	401
Other	334	148
Total current assets	3,881	3,304
Property, Plant and Equipment [Abstract]
Cost	47,323	44,864
Accumulated depreciation and amortization	(15,857)	(15,212)
Generation facilities to be retired, net	421	529
Net property, plant and equipment	31,887	30,181
Other Noncurrent Assets
Goodwill	3,655	3,655
Regulatory assets	6,010	5,722
Nuclear decommissioning trust funds	3,324	2,932
Other	931	856
Total other noncurrent assets	13,920	13,165
Total Assets	49,688	46,650
Current Liabilities [Abstract]
Accounts payable	1,006	1,003
Accounts payable to affiliated companies	251	348
Notes payable to affiliated companies	805	729
Taxes accrued	101	83
Interest accrued	212	201
Current maturities of long-term debt	771	778
Asset retirement obligations	295	189
Regulatory liabilities	213	189
Other	729	745
Total current liabilities	4,383	4,265
Long-Term Debt	16,916	15,590
Long-Term Debt Payable to Affiliated Companies	150	1,173
Other Noncurrent Liabilities [Abstract]
Deferred income taxes	3,502	5,246
Asset retirement obligations	5,119	5,286
Regulatory liabilities	5,306	2,395
Accrued pension and other post-retirement benefit costs	545	547
Other	302	341
Total other noncurrent liabilities	14,774	13,815
Commitments and Contingencies
Equity [Abstract]
Additional paid-in capital	9,143	8,094
Retained earnings	4,350	3,764
Accumulated other comprehensive (loss) income	(25)	(38)
Total Parent stockholders' equity	13,468	11,820
Noncontrolling interests	(3)	(13)
Total equity	13,465	11,807
Total Liabilities and Equity	49,688	46,650
Duke Energy Progress [Member]
Current Assets [Abstract]
Cash and cash equivalents	20	11
Receivables (net of allowance for doubtful accounts)	56	51
Receivables of VIEs (net of allowance for doubtful accounts)	459	404
Receivables from affiliated companies	3	5
Notes receivable from affiliated companies		165
Inventory	1,017	1,076
Regulatory assets	352	188
Other	97	57
Total current assets	2,004	1,957
Property, Plant and Equipment [Abstract]
Cost	29,583	28,419
Accumulated depreciation and amortization	(10,903)	(10,561)
Generation facilities to be retired, net	421	529
Net property, plant and equipment	19,101	18,387
Other Noncurrent Assets
Regulatory assets	3,507	3,243
Nuclear decommissioning trust funds	2,588	2,217
Other	599	525
Total other noncurrent assets	6,694	5,985
Total Assets	27,799	26,329
Current Liabilities [Abstract]
Accounts payable	402	589
Accounts payable to affiliated companies	179	227
Notes payable to affiliated companies	240
Taxes accrued	64	104
Interest accrued	102	102
Current maturities of long-term debt	3	452
Asset retirement obligations	295	189
Regulatory liabilities	139	158
Other	376	365
Total current liabilities	1,800	2,186
Long-Term Debt	7,204	6,409
Long-Term Debt Payable to Affiliated Companies	150	150
Other Noncurrent Liabilities [Abstract]
Deferred income taxes	1,883	3,323
Asset retirement obligations	4,378	4,508
Regulatory liabilities	3,999	1,946
Accrued pension and other post-retirement benefit costs	248	252
Investment tax credits	143	146
Other	45	51
Total other noncurrent liabilities	10,696	10,226
Equity [Abstract]
Total member's equity	7,949	7,358
Total Liabilities and Equity	27,799	26,329
Duke Energy Florida [Member]
Current Assets [Abstract]
Cash and cash equivalents	13	16
Receivables (net of allowance for doubtful accounts)	65	61
Receivables of VIEs (net of allowance for doubtful accounts)	321	288
Receivables from affiliated companies	2	5
Notes receivable from affiliated companies	313
Inventory	574	641
Regulatory assets	389	213
Other	86	125
Total current assets	1,763	1,349
Property, Plant and Equipment [Abstract]
Cost	17,730	16,434
Accumulated depreciation and amortization	(4,947)	(4,644)
Net property, plant and equipment	12,783	11,790
Other Noncurrent Assets
Regulatory assets	2,503	2,480
Nuclear decommissioning trust funds	736	715
Other	284	278
Total other noncurrent assets	3,523	3,473
Total Assets	18,069	16,612
Current Liabilities [Abstract]
Accounts payable	602	413
Accounts payable to affiliated companies	74	125
Notes payable to affiliated companies		297
Taxes accrued	34	33
Interest accrued	56	49
Current maturities of long-term debt	768	326
Regulatory liabilities	74	31
Other	334	352
Total current liabilities	1,942	1,626
Long-Term Debt	6,327	5,799
Other Noncurrent Liabilities [Abstract]
Deferred income taxes	1,761	2,694
Asset retirement obligations	742	778
Regulatory liabilities	1,307	448
Accrued pension and other post-retirement benefit costs	264	262
Other	108	105
Total other noncurrent liabilities	4,182	4,287
Equity [Abstract]
Member's equity	5,614	4,899
Accumulated other comprehensive (loss) income	4	1
Total member's equity	5,618	4,900
Total Liabilities and Equity	18,069	16,612
Duke Energy Ohio [Member]
Current Assets [Abstract]
Cash and cash equivalents	12	13
Receivables (net of allowance for doubtful accounts)	68	71
Receivables from affiliated companies	133	129
Notes receivable from affiliated companies	14	94
Inventory	133	137
Regulatory assets	49	37
Other	39	37
Total current assets	448	518
Property, Plant and Equipment [Abstract]
Cost	8,732	8,126
Accumulated depreciation and amortization	(2,691)	(2,579)
Net property, plant and equipment	6,041	5,547
Other Noncurrent Assets
Goodwill	920	920
Regulatory assets	445	520
Other	21	23
Total other noncurrent assets	1,386	1,463
Total Assets	7,875	7,528
Current Liabilities [Abstract]
Accounts payable	313	282
Accounts payable to affiliated companies	62	63
Notes payable to affiliated companies	29	16
Taxes accrued	190	178
Interest accrued	21	19
Current maturities of long-term debt	3	1
Asset retirement obligations	3
Regulatory liabilities	36	21
Other	71	91
Total current liabilities	728	671
Long-Term Debt	2,039	1,858
Long-Term Debt Payable to Affiliated Companies	25	25
Other Noncurrent Liabilities [Abstract]
Deferred income taxes	781	1,443
Asset retirement obligations	81	77
Regulatory liabilities	891	236
Accrued pension and other post-retirement benefit costs	59	56
Other	108	166
Total other noncurrent liabilities	1,920	1,978
Equity [Abstract]
Common stock	762	762
Additional paid-in capital	2,670	2,695
Retained earnings	(269)	(461)
Total Parent stockholders' equity	3,163	2,996
Total Liabilities and Equity	7,875	7,528
Duke Energy Indiana [Member]
Current Assets [Abstract]
Cash and cash equivalents	9	17
Receivables (net of allowance for doubtful accounts)	57	105
Receivables from affiliated companies	125	114
Notes receivable from affiliated companies		86
Inventory	450	504
Regulatory assets	165	149
Other	30	45
Total current assets	836	1,020
Property, Plant and Equipment [Abstract]
Cost	14,948	14,241
Accumulated depreciation and amortization	(4,662)	(4,317)
Net property, plant and equipment	10,286	9,924
Other Noncurrent Assets
Regulatory assets	978	1,073
Other	189	147
Total other noncurrent assets	1,167	1,220
Total Assets	12,289	12,164
Current Liabilities [Abstract]
Accounts payable	196	263
Accounts payable to affiliated companies	78	74
Notes payable to affiliated companies	161	0
Taxes accrued	95	31
Interest accrued	57	61
Current maturities of long-term debt	3	3
Asset retirement obligations	54
Regulatory liabilities	24	40
Other	104	93
Total current liabilities	772	565
Long-Term Debt	3,630	3,633
Long-Term Debt Payable to Affiliated Companies	150	150
Other Noncurrent Liabilities [Abstract]
Deferred income taxes	925	1,900
Asset retirement obligations	727	866
Regulatory liabilities	1,723	748
Accrued pension and other post-retirement benefit costs	76	71
Investment tax credits	147	137
Other	18	27
Total other noncurrent liabilities	3,616	3,749
Equity [Abstract]
Total member's equity	4,121	4,067
Total Liabilities and Equity	12,289	12,164
Piedmont Natural Gas [Member]
Current Assets [Abstract]
Cash and cash equivalents	19	25
Receivables (net of allowance for doubtful accounts)	275	232
Receivables from affiliated companies	7	7
Inventory	66	66
Regulatory assets	95	124
Other	52	21
Total current assets	514	475
Property, Plant and Equipment [Abstract]
Cost	6,725	6,174
Accumulated depreciation and amortization	(1,479)	(1,360)
Net property, plant and equipment	5,246	4,814
Other Noncurrent Assets
Goodwill	49	49
Regulatory assets	283	373
Investments in equity method unconsolidated affiliates	61	212
Other	65	21
Total other noncurrent assets	458	655
Total Assets	6,218	5,944
Current Liabilities [Abstract]
Accounts payable	125	155
Accounts payable to affiliated companies	13	8
Notes payable and commercial paper		330
Notes payable to affiliated companies	364
Taxes accrued	19	67
Interest accrued	31	33
Current maturities of long-term debt	250	35
Regulatory liabilities	3	0
Other	69	102
Total current liabilities	874	730
Long-Term Debt	1,787	1,786
Other Noncurrent Liabilities [Abstract]
Deferred income taxes	564	931
Asset retirement obligations	15	14
Regulatory liabilities	1,141	608
Accrued pension and other post-retirement benefit costs	5	14
Other	170	189
Total other noncurrent liabilities	1,895	1,756
Equity [Abstract]
Common stock	860	860
Retained earnings	802	812
Total Parent stockholders' equity	1,662	1,672
Total Liabilities and Equity	$ 6,218	$ 5,944