Asset Retirement Obligations (ARO by Category) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Asset Retirement Obligations [Line Items]
Total ARO	$ 13,654	$ 13,318
Less: Current portion	742	881
Total noncurrent ARO	12,912	12,437
Duke Energy Carolinas
Asset Retirement Obligations [Line Items]
Total ARO	5,774	5,734
Less: Current portion	267	206
Total noncurrent ARO	5,507	5,528
Progress Energy
Asset Retirement Obligations [Line Items]
Total ARO	6,355	6,471
Less: Current portion	297	485
Total noncurrent ARO	6,058	5,986
Duke Energy Progress
Asset Retirement Obligations [Line Items]
Total ARO	5,800	5,893
Less: Current portion	297	485
Total noncurrent ARO	5,503	5,408
Duke Energy Florida
Asset Retirement Obligations [Line Items]
Total ARO	555	578
Total noncurrent ARO	555	578
Duke Energy Ohio
Asset Retirement Obligations [Line Items]
Total ARO	91	80
Less: Current portion	7	1
Total noncurrent ARO	84	79
Duke Energy Indiana
Asset Retirement Obligations [Line Items]
Total ARO	1,214	832
Less: Current portion	170	189
Total noncurrent ARO	1,044	643
Piedmont Natural Gas
Asset Retirement Obligations [Line Items]
Total ARO	17	17
Total noncurrent ARO	17	$ 17
Decommissioning of nuclear power facilities
Asset Retirement Obligations [Line Items]
Total ARO	6,815
Decommissioning of nuclear power facilities | Duke Energy Carolinas
Asset Retirement Obligations [Line Items]
Total ARO	2,658
Decommissioning of nuclear power facilities | Progress Energy
Asset Retirement Obligations [Line Items]
Total ARO	4,107
Decommissioning of nuclear power facilities | Duke Energy Progress
Asset Retirement Obligations [Line Items]
Total ARO	3,606
Decommissioning of nuclear power facilities | Duke Energy Florida
Asset Retirement Obligations [Line Items]
Total ARO	501
Closure of ash impoundments
Asset Retirement Obligations [Line Items]
Total ARO	6,458
Closure of ash impoundments | Duke Energy Carolinas
Asset Retirement Obligations [Line Items]
Total ARO	3,049
Closure of ash impoundments | Progress Energy
Asset Retirement Obligations [Line Items]
Total ARO	2,172
Closure of ash impoundments | Duke Energy Progress
Asset Retirement Obligations [Line Items]
Total ARO	2,150
Closure of ash impoundments | Duke Energy Florida
Asset Retirement Obligations [Line Items]
Total ARO	22
Closure of ash impoundments | Duke Energy Ohio
Asset Retirement Obligations [Line Items]
Total ARO	51
Closure of ash impoundments | Duke Energy Indiana
Asset Retirement Obligations [Line Items]
Total ARO	1,186
Other
Asset Retirement Obligations [Line Items]
Total ARO	381
Other | Duke Energy Carolinas
Asset Retirement Obligations [Line Items]
Total ARO	67
Other | Progress Energy
Asset Retirement Obligations [Line Items]
Total ARO	76
Other | Duke Energy Progress
Asset Retirement Obligations [Line Items]
Total ARO	44
Other | Duke Energy Florida
Asset Retirement Obligations [Line Items]
Total ARO	32
Other | Duke Energy Ohio
Asset Retirement Obligations [Line Items]
Total ARO	40
Other | Duke Energy Indiana
Asset Retirement Obligations [Line Items]
Total ARO	28
Other | Piedmont Natural Gas
Asset Retirement Obligations [Line Items]
Total ARO	$ 17