Related Party Transactions (Narrative) (Details) (USD $)		9 Months Ended							9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 DECAM [Member]	Sep. 30, 2014 Parent Company [Member]	Sep. 30, 2014 Duke Energy Ohio [Member]	Dec. 31, 2013 Duke Energy Ohio [Member]	Sep. 30, 2014 Duke Energy Ohio [Member] DECAM [Member]	Dec. 31, 2013 Duke Energy Ohio [Member] DECAM [Member]	Apr. 30, 2014 Unsecured Debt [Member] Parent Company [Member]	Sep. 30, 2014 Unsecured Debt [Member] Duke Energy Ohio [Member]	Sep. 30, 2014 April 2014 0.612% Senior Unsecured Floating Notes Maturing April 2017 [Member] Unsecured Debt [Member]		Sep. 30, 2014 April 2014 0.612% Senior Unsecured Floating Notes Maturing April 2017 [Member] Unsecured Debt [Member] Parent Company [Member]
Related Party Transaction [Line Items]
Intercompany loan payable				$ 563,000,000	$ 43,000,000	$ 550,000,000	$ 43,000,000
Debt issuances	2,222,000,000		1,000,000,000					1,000,000,000		400,000,000	[1]	400,000,000	[1]
Proceeds from Issuance of Debt		400,000,000
Proceeds from (Repayments of) Debt									$ 402,000,000

[1] Proceeds were used to redeem $402 million of tax-exempt bonds at Duke Energy Ohio, the repayment of outstanding commercial paper and for general corporate purposes. See Note 9 for additional information related to the redemption of Duke Energy Ohio's tax-exempt bonds.