Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 381	$ 390
Investments and other assets	3,227	3,432
Other current liabilities	1,786	1,996
Deferred credits and other liabilities	26,878	26,575
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	178	213
Intangibles, net		96
Investments and other assets	4	4
Total assets	182	313
Other current liabilities	3	3
Deferred credits and other liabilities	14	15
Total liabilities	17	18
Net assets (liabilities)	165	295
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	152	153
Total assets	152	153
Net assets (liabilities)	152	153
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	26	60
Intangibles, net		96
Investments and other assets	4	4
Total assets	30	160
Other current liabilities	3	3
Deferred credits and other liabilities	14	15
Total liabilities	17	18
Net assets (liabilities)	13	142
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Investments and other assets	19	232
Other current liabilities	78	110
Deferred credits and other liabilities	2,080	2,546
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables (net of allowance for doubtful accounts)	68	114
Intangibles, net		96
Total assets	68	210
Net assets (liabilities)	68	210
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Investments and other assets	218	269
Other current liabilities	125	88
Deferred credits and other liabilities	2,422	2,334
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables (net of allowance for doubtful accounts)	98	143
Total assets	98	143
Net assets (liabilities)	$ 98	$ 143