Severance Rollforward (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Restructuring Liability, beginning balance	$ 32
Provision/Adjustments	118
Cash Reductions	39
Restructuring Liability, ending balance	111
Acquired Severance Liability	12
Duke Energy Carolinas [Member]
Restructuring Liability, beginning balance	1
Provision/Adjustments	14
Cash Reductions	5
Restructuring Liability, ending balance	$ 10