Asset Retirement Obligation (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Asset Retirement Obligation [Line Items]
Decommissioning Fund Investments, Fair Value	$ 3,941	$ 1,797
Duke Energy Carolinas [Member]
Asset Retirement Obligation [Line Items]
Decommissioning Fund Investments, Fair Value	2,053	1,797
Contribution and expense amounts for Decommissioning	48	48	48
Duke Energy Carolinas [Member] | Study 2008 [Member]
Asset Retirement Obligation [Line Items]
Decommissioning cost study estimate	3,000
Progress Energy [Member]
Asset Retirement Obligation [Line Items]
Decommissioning Fund Investments, Fair Value	0	0
Progress Energy Carolinas [Member]
Asset Retirement Obligation [Line Items]
Decommissioning Fund Investments, Fair Value	0	0
Contribution and expense amounts for Decommissioning	31	31
Progress Energy Carolinas [Member] | Study 2009 [Member]
Asset Retirement Obligation [Line Items]
Decommissioning cost study estimate	3,000
Progress Energy Florida [Member]
Asset Retirement Obligation [Line Items]
Decommissioning Fund Investments, Fair Value	0	0
Progress Energy Florida [Member] | Study 2008 [Member]
Asset Retirement Obligation [Line Items]
Decommissioning cost study estimate	751
Progress Energy Florida [Member] | Study 2011 [Member]
Asset Retirement Obligation [Line Items]
Decommissioning cost study estimate	$ 989