Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 547	$ 499
Investments and other assets	3,036	3,042
Other current liabilities	1,965	2,115
Deferred credits and other liabilities	32,645	32,490
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	413	387
Total assets	413	387
Other current liabilities	2	3
Deferred credits and other liabilities	14	14
Total liabilities	16	17
Net assets	397	370
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	227	235
Total assets	227	235
Net assets	227	235
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	186	152
Total assets	186	152
Other current liabilities	2	3
Deferred credits and other liabilities	14	14
Total liabilities	16	17
Net assets	170	135
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	93	84
Investments and other assets	20	20
Other current liabilities	151	153
Deferred credits and other liabilities	2,016	1,998
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	39	47
Total assets	39	47
Net assets	39	47
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	64	71
Other current liabilities	78	97
Deferred credits and other liabilities	3,210	3,219
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	50	60
Total assets	50	60
Net assets	$ 50	$ 60