Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Variable Interest Entities [Line Items]
Other noncurrent assets	$ 2,826	$ 2,769
Taxes accrued	432	384
Current Liabilities: Other	1,708	2,044
Deferred income taxes	14,695	14,155
Noncurrent Liabilities: Other	1,651	1,753
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	1,068	751
Other noncurrent assets	12	12
Total assets	1,080	763
Current Liabilities: Other	10	3
Noncurrent Liabilities: Other	13	13
Total liabilities	23	16
Net assets	1,057	747
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	800	487
Other noncurrent assets	12	12
Total assets	812	499
Current Liabilities: Other	10
Total liabilities	10
Net assets	802	499
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	176	174
Total assets	176	174
Net assets	176	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		3
Noncurrent Liabilities: Other	13	13
Total liabilities	13	16
Net assets	79	74
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	74	129
Other noncurrent assets	23	23
Taxes accrued	100	178
Current Liabilities: Other	77	91
Deferred income taxes	1,506	1,443
Noncurrent Liabilities: Other	157	166
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	44	82
Total assets	44	82
Net assets	44	82
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	87	114
Other noncurrent assets	159	147
Taxes accrued	28	31
Current Liabilities: Other	122	93
Deferred income taxes	2,011	1,900
Noncurrent Liabilities: Other	23	27
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	72	101
Total assets	72	101
Net assets	72	101
Piedmont Natural Gas [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	8	7
Other noncurrent assets	12	21
Taxes accrued	21	67
Current Liabilities: Other	67	102
Deferred income taxes	1,019	931
Noncurrent Liabilities: Other	$ 164	189
Piedmont Natural Gas [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates		139
Total assets		139
Noncurrent Liabilities: Other		4
Total liabilities		4
Net assets		$ 135