Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 604	$ 499
Investments and other assets	2,948	3,042
Other current liabilities	1,728	2,115
Deferred credits and other liabilities	33,100	32,490
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	485	387
Investments and other assets	12
Total assets	497	387
Other current liabilities	2	3
Deferred credits and other liabilities	13	14
Total liabilities	15	17
Net assets	482	370
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	168	235
Total assets	168	235
Net assets	168	235
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	317	152
Investments and other assets	12
Total assets	329	152
Other current liabilities	2	3
Deferred credits and other liabilities	13	14
Total liabilities	15	17
Net assets	314	135
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	96	84
Investments and other assets	18	20
Other current liabilities	84	153
Deferred credits and other liabilities	1,987	1,998
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	50	47
Total assets	50	47
Net assets	50	47
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	74	71
Other current liabilities	95	97
Deferred credits and other liabilities	3,710	3,219
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	74	60
Total assets	74	60
Net assets	$ 74	$ 60