Leases (Lease Costs) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases		$ 221
Operating lease expense	$ 75	220
Short-term lease expense	2	15
Variable lease expense	27	48
Finance lease expense
Amortization of leased assets	28	84
Interest on lease liabilities	7	44
Total finance lease expense	35	128
Total lease expense	139	411
Operating cash flows from finance leases		44
Financing cash flows from finance leases		84
Finance		175
Operating, lease assets obtained		147
Duke Energy Carolinas [Member]
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases		26
Operating lease expense	13	36
Short-term lease expense		4
Variable lease expense	6	18
Finance lease expense
Amortization of leased assets	2	4
Interest on lease liabilities	3	10
Total finance lease expense	5	14
Total lease expense	24	72
Operating cash flows from finance leases		10
Financing cash flows from finance leases		4
Operating, lease assets obtained		44
Progress Energy [Member]
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases		104
Operating lease expense	39	121
Short-term lease expense		7
Variable lease expense	22	29
Finance lease expense
Amortization of leased assets	9	17
Interest on lease liabilities	12	31
Total finance lease expense	21	48
Total lease expense	82	205
Operating cash flows from finance leases		31
Financing cash flows from finance leases		17
Finance		175
Operating, lease assets obtained		30
Duke Energy Progress [Member]
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases		43
Operating lease expense	16	52
Short-term lease expense		3
Variable lease expense	21	24
Finance lease expense
Amortization of leased assets	1	3
Interest on lease liabilities	10	24
Total finance lease expense	11	27
Total lease expense	48	106
Operating cash flows from finance leases		24
Financing cash flows from finance leases		3
Finance		175
Operating, lease assets obtained		30
Duke Energy Florida [Member]
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases		61
Operating lease expense	23	69
Short-term lease expense		4
Variable lease expense	1	5
Finance lease expense
Amortization of leased assets	8	14
Interest on lease liabilities	2	7
Total finance lease expense	10	21
Total lease expense	34	99
Operating cash flows from finance leases		7
Financing cash flows from finance leases		14
Duke Energy Ohio [Member]
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases		1
Operating lease expense	3	9
Short-term lease expense		1
Finance lease expense
Amortization of leased assets		1
Total finance lease expense		1
Total lease expense	3	11
Financing cash flows from finance leases		1
Duke Energy Indiana [Member]
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases		5
Operating lease expense	5	15
Short-term lease expense	1	2
Finance lease expense
Interest on lease liabilities		1
Total finance lease expense		1
Total lease expense	6	18
Operating cash flows from finance leases		1
Piedmont Natural Gas [Member]
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases		6
Operating lease expense	1	4
Finance lease expense
Total lease expense	$ 1	4
Operating, lease assets obtained		$ 1