Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 343	$ 358
Investments and other assets	3,207us-gaap_OtherAssetsNoncurrent	3,008us-gaap_OtherAssetsNoncurrent
Other current liabilities	2,014us-gaap_OtherLiabilitiesCurrent	2,188us-gaap_OtherLiabilitiesCurrent
Deferred credits and other liabilities	31,979	31,364
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	213	188
Investments and other assets	3	4
Total assets	216	192
Other current liabilities	2	3
Deferred credits and other liabilities	14	14
Total liabilities	16	17
Net assets (liabilities)	200	175
Renewables [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	147	150
Total assets	147	150
Net assets (liabilities)	147	150
Other VIEs [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	66	38
Investments and other assets	3	4
Total assets	69	42
Other current liabilities	2	3
Deferred credits and other liabilities	14	14
Total liabilities	16	17
Net assets (liabilities)	53	25
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Investments and other assets	35	23
Other current liabilities	64	66
Deferred credits and other liabilities	2,298	2,281
Duke Energy Ohio [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables (net of allowance for doubtful accounts)	90	91
Total assets	90	91
Net assets (liabilities)	90	91
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Investments and other assets	257	251
Other current liabilities	88	98
Deferred credits and other liabilities	2,777	2,730
Duke Energy Indiana [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables (net of allowance for doubtful accounts)	105	113
Total assets	105	113
Net assets (liabilities)	$ 105	$ 113

For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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Net carrying amount of the assets and liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), when the reporting entity is not the VIE's primary beneficiary.

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