Income Taxes (Summary of Tax Credits and NOL Carryforwards) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Operating Loss Carryforwards [Line Items]
Investment Tax Credits	$ 391
Alternative Minimum Tax Credits	1,033
Tax credit carryforwards	3,311		930
Valuation allowance	226		144
Duke Energy Carolinas [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	447		199
Progress Energy [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	1,536		1,163
Valuation allowance	77		71
Progress Energy Carolinas [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	309		57
Progress Energy Florida [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	91		42
Duke Energy Ohio [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	152
Valuation allowance	1
Duke Energy Indiana [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	340		95
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	1,604
State [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	166	[1]
Valuation allowance	(121)
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	117	[2]
Valuation allowance	$ (105)

[1] A valuation allowance of $121 million has been recorded on the state NOL carryforwards and state capital loss carryforwards, as presented in the Net Deferred Income Tax Liability Components table.

[2] A valuation allowance of $105 million has been recorded on the foreign NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table.