Investments In Debt And Equity Securities (Maturities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Debt Instrument [Line Items]
1 year	$ 312
1 through 5 years	403
6 to 10 years	392
Thereafter	774
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
1 year	1
1 through 5 years	153
6 to 10 years	201
Thereafter	374
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
1 year	1
1 through 5 years	21
6 to 10 years	3
Thereafter	3
Progress Energy [Member]
Debt Instrument [Line Items]
1 year	26
1 through 5 years	134
6 to 10 years	154
Thereafter	318
Progress Energy Carolinas [Member]
Debt Instrument [Line Items]
1 year	15
1 through 5 years	116
6 to 10 years	70
Thereafter	208
Progress Energy Florida [Member]
Debt Instrument [Line Items]
1 year	10
1 through 5 years	18
6 to 10 years	84
Thereafter	$ 111