Organization and Basis of Presentation (Schedule of New Accounting Pronouncements) (Details) - ASU 2016-13 $ in Millions	Jan. 01, 2020 USD ($)
Retained Earnings Adjustments [Line Items]
Total pretax impact to Retained Earnings	$ 120
Duke Energy Carolinas
Retained Earnings Adjustments [Line Items]
Total pretax impact to Retained Earnings	16
Progress Energy
Retained Earnings Adjustments [Line Items]
Total pretax impact to Retained Earnings	2
Duke Energy Progress
Retained Earnings Adjustments [Line Items]
Total pretax impact to Retained Earnings	1
Duke Energy Florida
Retained Earnings Adjustments [Line Items]
Total pretax impact to Retained Earnings	1
Piedmont Natural Gas
Retained Earnings Adjustments [Line Items]
Total pretax impact to Retained Earnings	$ 1