Asset Retirement Obligations (ARO Rollforward) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	$ 4,958	[1],[2]
Accretion expense	164	[3]
Liabilities settled	(56)
Liabilities incurred in the current year	3,433	[4]
Balance at end of period	8,499
Duke Energy Carolinas [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	1,594
Accretion expense	71	[3]
Liabilities settled
Liabilities incurred in the current year	2,026	[4]
Balance at end of period	3,691
Progress Energy [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	2,570	[2]
Accretion expense	91	[3]
Liabilities settled	(52)
Liabilities incurred in the current year	1,406	[4]
Balance at end of period	4,015
Duke Energy Progress [Member]
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	1,737	[2]
Accretion expense	63	[3]
Liabilities settled
Liabilities incurred in the current year	1,406	[4]
Balance at end of period	3,206
Asset retirement obligation, current	$ 8

[1] The balance as of December 31, 2013 primarily relates to decommissioning nuclear power facilities, asbestos removal and closure of landfills at fossil generation facilities.

[2] The balance at December 31, 2013 includes $8 million reported in Other current liabilities on the Condensed Consolidated Balance Sheets at Duke Energy, Progress Energy and Duke Energy Progress.

[3] Substantially all accretion expense for the nine months ended September 30, 2014 relates to Duke Energy's regulated electric operations from previously established asset retirement obligations and has been deferred in accordance with regulatory accounting treatment.

[4] Amounts relate to asset obligations recorded in the third quarter of 2014 as a result of the Coal Ash Act and an agreement with the SCDHEC related to the W.S Lee Steam Station.