Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entities [Line Items]
Other noncurrent assets	$ 2,754	$ 2,769
Taxes accrued	363	384
Current Liabilities: Other	1,570	2,044
Deferred income taxes	14,443	14,155
Noncurrent Liabilities: Other	1,707	1,753
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	938	751
Other noncurrent assets	12	12
Total assets	950	763
Taxes accrued	23
Current Liabilities: Other	2	3
Deferred income taxes	(7)
Noncurrent Liabilities: Other	13	13
Total liabilities	31	16
Net assets	919	747
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	673	487
Other noncurrent assets	12	12
Total assets	685	499
Taxes accrued	23
Deferred income taxes	(7)
Total liabilities	16
Net assets	669	499
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	173	174
Total assets	173	174
Net assets	173	174
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	92	90
Total assets	92	90
Current Liabilities: Other	2	3
Noncurrent Liabilities: Other	13	13
Total liabilities	15	16
Net assets	77	74
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	88	129
Other noncurrent assets	23	23
Taxes accrued	127	178
Current Liabilities: Other	83	91
Deferred income taxes	1,472	1,443
Noncurrent Liabilities: Other	166	166
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	53	82
Total assets	53	82
Net assets	53	82
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	88	114
Other noncurrent assets	156	147
Taxes accrued	72	31
Current Liabilities: Other	75	93
Deferred income taxes	1,921	1,900
Noncurrent Liabilities: Other	24	27
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	69	101
Total assets	69	101
Net assets	69	101
Piedmont Natural Gas [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	7	7
Other noncurrent assets	19	21
Taxes accrued	69	67
Current Liabilities: Other	70	102
Deferred income taxes	981	931
Noncurrent Liabilities: Other	169	189
Piedmont Natural Gas [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	152	139
Total assets	152	139
Taxes accrued	(1)
Deferred income taxes	4
Noncurrent Liabilities: Other		4
Total liabilities	3	4
Net assets	149	135
Piedmont Natural Gas [Member] | Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 152	$ 139