Severance VOP Deferral (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restructuring Cost and Reserve [Line Items]
Voluntary opportunity cost deferral	$ (101)	$ 0	$ 0
Duke Energy Carolinas [Member]
Restructuring Cost and Reserve [Line Items]
Voluntary opportunity cost deferral	$ (101)	$ 0	$ 0