Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 375	$ 358
Investments and other assets	3,239	3,008
Other current liabilities	1,976	2,188
Deferred credits and other liabilities	32,517	31,364
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	247	188
Investments and other assets	1	4
Total assets	248	192
Other current liabilities	3	3
Deferred credits and other liabilities	14	14
Total liabilities	17	17
Net assets	231	175
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	149	150
Total assets	149	150
Total liabilities	0
Net assets	149	150
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	98	38
Investments and other assets	1	4
Total assets	99	42
Other current liabilities	3	3
Deferred credits and other liabilities	14	14
Total liabilities	17	17
Net assets	82	25
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Investments and other assets	16	23
Other current liabilities	154	66
Deferred credits and other liabilities	1,944	2,281
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables	52	91
Total assets	52	91
Total liabilities	0
Net assets	52	91
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Investments and other assets	250	251
Other current liabilities	90	98
Deferred credits and other liabilities	3,202	2,730
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables	80	113
Total assets	80	113
Total liabilities	0
Net assets	$ 80	$ 113