Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Impairment charges	$ 81us-gaap_AssetImpairmentCharges	$ 399us-gaap_AssetImpairmentCharges	$ 666us-gaap_AssetImpairmentCharges
Investments in equity method unconsolidated affiliates	358	390
Investments and other assets	3,008us-gaap_OtherAssetsNoncurrent	3,432us-gaap_OtherAssetsNoncurrent
Other current liabilities	2,188us-gaap_OtherLiabilitiesCurrent	1,996us-gaap_OtherLiabilitiesCurrent
Other liabilities	31,364	26,575
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	188	213
Intangibles, net		96
Investments and other assets	4	4
Total assets	192	313
Other current liabilities	3	3
Other liabilities	14	15
Total liabilities	17	18
Net assets of non-consolidated VIEs	175	295
Renewables [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	150	153
Total assets	150	153
Net assets of non-consolidated VIEs	150	153
Other VIEs [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	38	60
Intangibles, net		96
Investments and other assets	4	4
Total assets	42	160
Other current liabilities	3	3
Other liabilities	14	15
Total liabilities	17	18
Net assets of non-consolidated VIEs	25	142
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Impairment charges	94	5	2
Investments and other assets	23	232
Other current liabilities	66	110
Other liabilities	2,281	2,546
Duke Energy Ohio [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Receivables	91	114
Intangibles, net		96
Total assets	91	210
Net assets of non-consolidated VIEs	91	210
Duke Energy Ohio [Member] \| Other VIEs [Member]
Variable Interest Entity [Line Items]
Impairment charges	94
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Impairment charges	0	0	579
Investments and other assets	251	269
Other current liabilities	98	88
Other liabilities	2,730	2,334
Duke Energy Indiana [Member] \| Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Receivables	113	143
Total assets	113	143
Net assets of non-consolidated VIEs	$ 113	$ 143

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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