v2.4.0.6
Employee Benefit Plans (Components Of Net Periodic Pension Costs) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Pension Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost $ 42 $ 23
Interest cost on benefit obligation 80 61
Expected return on plan assets (137) (94)
Amortization of prior service cost (credit) (3) 1
Amortization of actuarial loss (gain) 61 24
Other 2 1
Net periodic costs 45 [1] 16 [1]
Regulatory asset amortization 3 3
Other Postretirement Benefit Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 7 2
Interest cost on benefit obligation 18 8
Expected return on plan assets (3) (4)
Amortization of prior service cost (credit) (3) (2)
Amortization of net transition liability   2
Amortization of actuarial loss (gain) 13 (2)
Net periodic costs 32 [2] 4 [2]
Regulatory asset amortization 2 2
Duke Energy Carolinas [Member] | Pension Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 12 9
Interest cost on benefit obligation 20 23
Expected return on plan assets (37) (36)
Amortization of prior service cost (credit) (2) 0
Amortization of actuarial loss (gain) 15 11
Other 1 0
Net periodic costs 9 7
Duke Energy Carolinas [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 1 1
Interest cost on benefit obligation 3 4
Expected return on plan assets (3) (3)
Amortization of prior service cost (credit) (2) (1)
Amortization of net transition liability   1
Amortization of actuarial loss (gain) 1 1
Net periodic costs 0 3
Progress Energy [Member] | Pension Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 15 15
Interest cost on benefit obligation 29 31
Expected return on plan assets (50) (46)
Amortization of prior service cost (credit) (1) 2
Amortization of actuarial loss (gain) 25 22
Other 1 0
Net periodic costs 19 24
Progress Energy [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 6 3
Interest cost on benefit obligation 11 10
Amortization of net transition liability   1
Amortization of actuarial loss (gain) 14 6
Net periodic costs 31 20
Duke Energy Progress [Member] | Pension Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 5 6
Interest cost on benefit obligation 13 14
Expected return on plan assets (23) (24)
Amortization of prior service cost (credit) 0 2
Amortization of actuarial loss (gain) 11 9
Other 0 0
Net periodic costs 6 7
Duke Energy Progress [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 3 1
Interest cost on benefit obligation 6 5
Amortization of actuarial loss (gain) 9 3
Net periodic costs 18 9
Duke Energy Florida [Member] | Pension Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 8 7
Interest cost on benefit obligation 13 13
Expected return on plan assets (22) (20)
Amortization of prior service cost (credit) 0 0
Amortization of actuarial loss (gain) 12 11
Other 0 0
Net periodic costs 11 11
Duke Energy Florida [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 2 1
Interest cost on benefit obligation 4 4
Amortization of net transition liability   1
Amortization of actuarial loss (gain) 4 3
Net periodic costs 10 9
Duke Energy Ohio [Member] | Pension Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 2 2
Interest cost on benefit obligation 5 8
Expected return on plan assets (8) (11)
Amortization of prior service cost (credit) 0 0
Amortization of actuarial loss (gain) 3 2
Other 0 0
Net periodic costs 2 [3] 1 [3]
Regulatory asset amortization 2 2
Duke Energy Ohio [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Interest cost on benefit obligation   1
Amortization of actuarial loss (gain)   (1)
Net periodic costs   0 [4]
Regulatory asset amortization 1 1
Duke Energy Indiana [Member] | Pension Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Service cost 3 2
Interest cost on benefit obligation 7 8
Expected return on plan assets (11) (12)
Amortization of prior service cost (credit) 0 1
Amortization of actuarial loss (gain) 6 3
Other 0 0
Net periodic costs 5 2
Duke Energy Indiana [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
    
Defined Benefit Plan Disclosure [Line Items]    
Interest cost on benefit obligation 1 2
Amortization of actuarial loss (gain) (1)  
Net periodic costs $ 0 $ 2
[1] Duke Energy amounts exclude $3 million for each of the three months ended March 31, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.
[2] Duke Energy amounts exclude $2 million for each of the three months ended March 31, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.
[3] Duke Energy Ohio amounts exclude $2 million for each of the three months ended March 31, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.
[4] Duke Energy Ohio amounts exclude $1 million for each of the three months ended March 31, 2013 and 2012, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy’s merger with Cinergy.