Asset Retirement Obligations Asset Retirement Obligations (ARO by Category) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Asset Retirement Obligations [Line Items]
Total ARO	$ 10,205	$ 10,611
Less: current portion	619	411
Total noncurrent ARO	9,586	10,200
Duke Energy Carolinas [Member]
Asset Retirement Obligations [Line Items]
Total ARO	3,601	3,895
Less: current portion	304	222
Total noncurrent ARO	3,297	3,673
Progress Energy [Member]
Asset Retirement Obligations [Line Items]
Total ARO	5,439	5,475
Less: current portion	250	189
Total noncurrent ARO	5,189	5,286
Duke Energy Progress [Member]
Asset Retirement Obligations [Line Items]
Total ARO	4,676	4,697
Less: current portion	250	189
Total noncurrent ARO	4,426	4,508
Duke Energy Florida [Member]
Asset Retirement Obligations [Line Items]
Total ARO	763	778
Total noncurrent ARO	763	778
Duke Energy Ohio [Member]
Asset Retirement Obligations [Line Items]
Total ARO	81	77
Less: current portion	6
Total noncurrent ARO	75	77
Duke Energy Indiana [Member]
Asset Retirement Obligations [Line Items]
Total ARO	793	866
Less: current portion	58
Total noncurrent ARO	735	866
Piedmont Natural Gas [Member]
Asset Retirement Obligations [Line Items]
Total ARO	15	14
Total noncurrent ARO	15	$ 14
Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligations [Line Items]
Total ARO	5,337
Decommissioning of Nuclear Power Facilities [Member] | Duke Energy Carolinas [Member]
Asset Retirement Obligations [Line Items]
Total ARO	1,916
Decommissioning of Nuclear Power Facilities [Member] | Progress Energy [Member]
Asset Retirement Obligations [Line Items]
Total ARO	3,235
Decommissioning of Nuclear Power Facilities [Member] | Duke Energy Progress [Member]
Asset Retirement Obligations [Line Items]
Total ARO	2,536
Decommissioning of Nuclear Power Facilities [Member] | Duke Energy Florida [Member]
Asset Retirement Obligations [Line Items]
Total ARO	699
Closure of Ash Impoundments [Member]
Asset Retirement Obligations [Line Items]
Total ARO	4,594
Closure of Ash Impoundments [Member] | Duke Energy Carolinas [Member]
Asset Retirement Obligations [Line Items]
Total ARO	1,650
Closure of Ash Impoundments [Member] | Progress Energy [Member]
Asset Retirement Obligations [Line Items]
Total ARO	2,124
Closure of Ash Impoundments [Member] | Duke Energy Progress [Member]
Asset Retirement Obligations [Line Items]
Total ARO	2,105
Closure of Ash Impoundments [Member] | Duke Energy Florida [Member]
Asset Retirement Obligations [Line Items]
Total ARO	19
Closure of Ash Impoundments [Member] | Duke Energy Ohio [Member]
Asset Retirement Obligations [Line Items]
Total ARO	42
Closure of Ash Impoundments [Member] | Duke Energy Indiana [Member]
Asset Retirement Obligations [Line Items]
Total ARO	777
Other [Member]
Asset Retirement Obligations [Line Items]
Total ARO	274
Other [Member] | Duke Energy Carolinas [Member]
Asset Retirement Obligations [Line Items]
Total ARO	35
Other [Member] | Progress Energy [Member]
Asset Retirement Obligations [Line Items]
Total ARO	80
Other [Member] | Duke Energy Progress [Member]
Asset Retirement Obligations [Line Items]
Total ARO	35
Other [Member] | Duke Energy Florida [Member]
Asset Retirement Obligations [Line Items]
Total ARO	45
Other [Member] | Duke Energy Ohio [Member]
Asset Retirement Obligations [Line Items]
Total ARO	39
Other [Member] | Duke Energy Indiana [Member]
Asset Retirement Obligations [Line Items]
Total ARO	16
Other [Member] | Piedmont Natural Gas [Member]
Asset Retirement Obligations [Line Items]
Total ARO	$ 15