Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Maximum years of participation	35 years
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of securities on loan	$ 305	$ 383
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Qualified Pension Plans [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Master trust allocation percentage	98.00%
Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	10 years
Other Post-Retirement Benefit Plans [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Master trust allocation percentage	2.00%
Duke Energy Carolinas [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Carolinas [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Progress Energy [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Progress Energy [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	10 years
Duke Energy Progress [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Progress [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	12 years
Duke Energy Florida [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Florida [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	17 years
Duke Energy Ohio [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Ohio [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Indiana [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Indiana [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years