Severance (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2012	Nov. 30, 2011 Employees	Dec. 31, 2013	Dec. 31, 2014 Employees
Restructuring Cost and Reserve [Line Items]
Voluntary opportunity cost deferral	$ 101
2011 Severance Plan [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees that accepted the termination benefits		1,100
Duke Energy Carolinas [Member]
Restructuring Cost and Reserve [Line Items]
Voluntary opportunity cost deferral	101
Duke Energy Florida [Member] | Crystal River Unit 3 2013 Severance Plan [Member]
Restructuring Cost and Reserve [Line Items]
Number of eligible employees	600
Deferred severance costs			$ 26
Duke Energy Ohio [Member] | Midwest Commercial Generation Involuntary Severance Plan [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees that accepted the termination benefits				50