Regulatory Matters (Schedule of Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Regulatory Assets Liabilities [Line Items]
Regulatory assets	$ 13,879	$ 13,901
Regulatory Assets, Current	1,437	1,023
Regulatory assets, noncurrent	12,442	12,878
Regulatory Liabilities	15,732	7,290
Regulatory Liability, Current	402	409
Regulatory Liability, Noncurrent	15,330	6,881
Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	5,968	5,613
Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	806	461
Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	8,113
Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	10	45
Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	20	83
Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	146	174
Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	47	192
Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	622	722
Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	4,025	3,761
Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	852	684
Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,249	2,387
Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	480	534
Debt Fair Value Adjustment [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,197	1,313
Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		894
Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	531	153
Nuclear asset securitized balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,142	1,193
Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	234	217
Derivatives - natural gas supply contracts [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	142	187
Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	530	407
Grid Modernization [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	39	65
Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	213	196
Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	507	156
Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	119	226
Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	366	413
Transmission Expansion Obligation [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	46	71
Manufactured Gas Plant [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	91	99
Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	362	218
NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	53	51
East Bend deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	45	32
Deferred pipeline integrity [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	54	36
Amounts due from customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	64	66
Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	538	542
Duke Energy Carolinas [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	3,152	3,397
Regulatory Assets, Current	299	238
Regulatory assets, noncurrent	2,853	3,159
Regulatory Liabilities	6,357	3,001
Regulatory Liability, Current	126	161
Regulatory Liability, Noncurrent	6,231	2,840
Duke Energy Carolinas [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	2,054	2,015
Duke Energy Carolinas [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	806	461
Duke Energy Carolinas [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	3,028
Duke Energy Carolinas [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	20	22
Duke Energy Carolinas [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	44	46
Duke Energy Carolinas [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	46	105
Duke Energy Carolinas [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	359	352
Duke Energy Carolinas [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,645	1,536
Duke Energy Carolinas [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		9
Duke Energy Carolinas [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	410	481
Duke Energy Carolinas [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	29	39
Duke Energy Carolinas [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		484
Duke Energy Carolinas [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	109	93
Duke Energy Carolinas [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	210	122
Duke Energy Carolinas [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	83	76
Duke Energy Carolinas [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	140
Duke Energy Carolinas [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	84	92
Duke Energy Carolinas [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	35	70
Duke Energy Carolinas [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	185	172
Duke Energy Carolinas [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	222	223
Progress Energy [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	6,751	6,123
Regulatory Assets, Current	741	401
Regulatory assets, noncurrent	6,010	5,722
Regulatory Liabilities	5,519	2,584
Regulatory Liability, Current	213	189
Regulatory Liability, Noncurrent	5,306	2,395
Progress Energy [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	2,537	2,198
Progress Energy [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	2,802
Progress Energy [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities		60
Progress Energy [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1	81
Progress Energy [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	179	245
Progress Energy [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,984	1,830
Progress Energy [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	655	569
Progress Energy [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	906	882
Progress Energy [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	386	422
Progress Energy [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		231
Progress Energy [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	526	148
Progress Energy [Member] | Nuclear asset securitized balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,142	1,193
Progress Energy [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	94	91
Progress Energy [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	281	278
Progress Energy [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	42	38
Progress Energy [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	349	111
Progress Energy [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	35	134
Progress Energy [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	38	42
Progress Energy [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	150
Progress Energy [Member] | NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	53	51
Progress Energy [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	110	103
Duke Energy Progress [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	3,859	3,431
Regulatory Assets, Current	352	188
Regulatory assets, noncurrent	3,507	3,243
Regulatory Liabilities	4,138	2,104
Regulatory Liability, Current	139	158
Regulatory Liability, Noncurrent	3,999	1,946
Duke Energy Progress [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	2,122	1,840
Duke Energy Progress [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1,854
Duke Energy Progress [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1	64
Duke Energy Progress [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	161	200
Duke Energy Progress [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,975	1,822
Duke Energy Progress [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	359	275
Duke Energy Progress [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	430	423
Duke Energy Progress [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	170	165
Duke Energy Progress [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		7
Duke Energy Progress [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	150	148
Duke Energy Progress [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	64	66
Duke Energy Progress [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	264	263
Duke Energy Progress [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	42	38
Duke Energy Progress [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	130	24
Duke Energy Progress [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	35	38
Duke Energy Progress [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	38	42
Duke Energy Progress [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	75
Duke Energy Progress [Member] | NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	53	51
Duke Energy Progress [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	74	69
Duke Energy Florida [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,892	2,693
Regulatory Assets, Current	389	213
Regulatory assets, noncurrent	2,503	2,480
Regulatory Liabilities	1,381	479
Regulatory Liability, Current	74	31
Regulatory Liability, Noncurrent	1,307	448
Duke Energy Florida [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	415	358
Duke Energy Florida [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	948
Duke Energy Florida [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities		60
Duke Energy Florida [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities		17
Duke Energy Florida [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	18	44
Duke Energy Florida [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	9	8
Duke Energy Florida [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	296	294
Duke Energy Florida [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	476	458
Duke Energy Florida [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	216	257
Duke Energy Florida [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		224
Duke Energy Florida [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	376
Duke Energy Florida [Member] | Nuclear asset securitized balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,142	1,193
Duke Energy Florida [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	30	25
Duke Energy Florida [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	17	15
Duke Energy Florida [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	219	87
Duke Energy Florida [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		96
Duke Energy Florida [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	75
Duke Energy Florida [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	36	36
Duke Energy Ohio [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	494	557
Regulatory Assets, Current	49	37
Regulatory assets, noncurrent	445	520
Regulatory Liabilities	927	257
Regulatory Liability, Current	36	21
Regulatory Liability, Noncurrent	891	236
Duke Energy Ohio [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	189	212
Duke Energy Ohio [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	688
Duke Energy Ohio [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	16	19
Duke Energy Ohio [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities		6
Duke Energy Ohio [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	34	20
Duke Energy Ohio [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	17	12
Duke Energy Ohio [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	139	135
Duke Energy Ohio [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		63
Duke Energy Ohio [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	5	5
Duke Energy Ohio [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	6	7
Duke Energy Ohio [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	18	6
Duke Energy Ohio [Member] | Grid Modernization [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	39	65
Duke Energy Ohio [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	5	4
Duke Energy Ohio [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		5
Duke Energy Ohio [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	19	20
Duke Energy Ohio [Member] | Transmission Expansion Obligation [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	50	71
Duke Energy Ohio [Member] | Manufactured Gas Plant [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	91	99
Duke Energy Ohio [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	6
Duke Energy Ohio [Member] | East Bend deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	45	32
Duke Energy Ohio [Member] | Deferred pipeline integrity [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	12	7
Duke Energy Ohio [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	42	26
Duke Energy Indiana [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,143	1,222
Regulatory Assets, Current	165	149
Regulatory assets, noncurrent	978	1,073
Regulatory Liabilities	1,747	788
Regulatory Liability, Current	24	40
Regulatory Liability, Noncurrent	1,723	748
Duke Energy Indiana [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	644	660
Duke Energy Indiana [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	998
Duke Energy Indiana [Member] | Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	10	45
Duke Energy Indiana [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	64	72
Duke Energy Indiana [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	31	11
Duke Energy Indiana [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	380	276
Duke Energy Indiana [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	197	222
Duke Energy Indiana [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	65	73
Duke Energy Indiana [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		119
Duke Energy Indiana [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	25	26
Duke Energy Indiana [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21
Duke Energy Indiana [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	11	10
Duke Energy Indiana [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	18	40
Duke Energy Indiana [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	274	281
Duke Energy Indiana [Member] | Gasification Services Agreement Buyout Costs [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		8
Duke Energy Indiana [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21	46
Duke Energy Indiana [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	131	121
Piedmont Natural Gas [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	378	497
Regulatory Assets, Current	95	124
Regulatory assets, noncurrent	283	373
Regulatory Liabilities	1,144	608
Regulatory Liability, Current	3	0
Regulatory Liability, Noncurrent	1,141	608
Piedmont Natural Gas [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	544	528
Piedmont Natural Gas [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	597	80
Piedmont Natural Gas [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	3	0
Piedmont Natural Gas [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	15	14
Piedmont Natural Gas [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	91	166
Piedmont Natural Gas [Member] | Derivatives - natural gas supply contracts [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	142	187
Piedmont Natural Gas [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	10	13
Piedmont Natural Gas [Member] | Deferred pipeline integrity [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	42	36
Piedmont Natural Gas [Member] | Amounts due from customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	64	66
Piedmont Natural Gas [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	$ 14	$ 15