Risk Management, Derivative Instruments and Hedging Activities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Derivative [Line Items]
Pretax deferred losses related to effective cash flow hedges	$ 65	$ 136
Amount expected to be recognized in earnings during the next 12 months	1
Undesignated commodity contracts latest expiration year	2017
Undesignated commodity contracts latest expiration year for terminated operations	2021
Duke Energy Carolinas [Member]
Derivative [Line Items]
Pretax deferred losses related to effective cash flow hedges	22
Progress Energy [Member]
Derivative [Line Items]
Pretax deferred losses related to effective cash flow hedges	60	71
Amount expected to be recognized in earnings during the next 12 months	5
Duke Energy Progress [Member]
Derivative [Line Items]
Pretax deferred losses related to effective cash flow hedges		1
Duke Energy Florida [Member]
Derivative [Line Items]
Pretax deferred losses related to effective cash flow hedges		$ 1