Derivatives and Hedging (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Derivative [Line Items]
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$ 10
Undesignated commodity contracts latest expiration year	2018
Duke Energy Carolinas [Member]
Derivative [Line Items]
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	3
Progress Energy [Member]
Derivative [Line Items]
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$ 13