Risk Management, Derivative Instruments and Hedging Activities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Derivative [Line Items]
Pretax deferred losses related to effective cash flow hedges	$ 70	$ 129
Amount expected to be recognized in earnings during the next 12 months	6
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	24	24
Progress Energy [Member]
Derivative [Line Items]
Pretax deferred losses related to effective cash flow hedges	63	235
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		118
Duke Energy Florida [Member]
Derivative [Line Items]
Pretax deferred losses related to effective cash flow hedges		$ 43