Related Party Transactions (Narrative) (Details) (USD $)		6 Months Ended						3 Months Ended		6 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 DECAM [Member]	Jun. 30, 2014 Parent Company [Member]	Jun. 30, 2014 Duke Energy Ohio [Member]	Dec. 31, 2013 Duke Energy Ohio [Member]	Jun. 30, 2014 Duke Energy Ohio [Member] DECAM [Member]	Dec. 31, 2013 Duke Energy Ohio [Member] DECAM [Member]	Jun. 30, 2014 MarkTo Market Of Commodity Contracts And Sales Of Power [Member] Duke Energy Ohio [Member] DECAM [Member]	Jun. 30, 2013 MarkTo Market Of Commodity Contracts And Sales Of Power [Member] Duke Energy Ohio [Member] DECAM [Member]	Jun. 30, 2014 MarkTo Market Of Commodity Contracts And Sales Of Power [Member] Duke Energy Ohio [Member] DECAM [Member]	Jun. 30, 2013 MarkTo Market Of Commodity Contracts And Sales Of Power [Member] Duke Energy Ohio [Member] DECAM [Member]	Apr. 01, 2014 Unsecured Debt [Member] Parent Company [Member]	Jun. 30, 2014 Unsecured Debt [Member] Duke Energy Ohio [Member]	Jun. 30, 2014 April 2014 0.610% Senior Unsecured Floating Notes Maturing April 2017 [Member] Unsecured Debt [Member]		Jun. 30, 2014 April 2014 0.610% Senior Unsecured Floating Notes Maturing April 2017 [Member] Unsecured Debt [Member] Parent Company [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party								$ 27,000,000	$ 12,000,000	$ 81,000,000	$ 6,000,000
Intercompany loan payable				828,000,000	43,000,000	802,000,000	43,000,000
Debt issuances	2,093,000,000		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 8 for additional information related to the redemption of Duke Energy Ohio's tax-exempt bonds.