Leases (Lease Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 283	$ 292
Short-term lease expense	4	16
Variable lease expense	30	47
Finance lease expense
Amortization of leased assets	119	111
Interest on lease liabilities	61	61
Total finance lease expense	180	172
Total lease expense	497	527
Duke Energy Carolinas
Lessee, Lease, Description [Line Items]
Operating lease expense	53	47
Short-term lease expense		5
Variable lease expense	13	22
Finance lease expense
Amortization of leased assets	8	6
Interest on lease liabilities	30	15
Total finance lease expense	38	21
Total lease expense	104	95
Progress Energy
Lessee, Lease, Description [Line Items]
Operating lease expense	162	161
Short-term lease expense	2	9
Variable lease expense	13	22
Finance lease expense
Amortization of leased assets	24	21
Interest on lease liabilities	44	42
Total finance lease expense	68	63
Total lease expense	245	255
Duke Energy Progress
Lessee, Lease, Description [Line Items]
Operating lease expense	72	69
Short-term lease expense	1	4
Variable lease expense	5	16
Finance lease expense
Amortization of leased assets	6	5
Interest on lease liabilities	37	33
Total finance lease expense	43	38
Total lease expense	121	127
Duke Energy Florida
Lessee, Lease, Description [Line Items]
Operating lease expense	90	92
Short-term lease expense	1	5
Variable lease expense	8	6
Finance lease expense
Amortization of leased assets	18	16
Interest on lease liabilities	7	9
Total finance lease expense	25	25
Total lease expense	124	128
Duke Energy Ohio
Lessee, Lease, Description [Line Items]
Operating lease expense	11	11
Short-term lease expense	0	1
Variable lease expense	0
Finance lease expense
Amortization of leased assets	0	1
Interest on lease liabilities	0	0
Total finance lease expense	0	1
Total lease expense	11	13
Duke Energy Indiana
Lessee, Lease, Description [Line Items]
Operating lease expense	19	20
Short-term lease expense	1	2
Variable lease expense	1	1
Finance lease expense
Amortization of leased assets	1	0
Interest on lease liabilities	0	1
Total finance lease expense	1	1
Total lease expense	22	24
Piedmont
Lessee, Lease, Description [Line Items]
Operating lease expense	7	5
Short-term lease expense	0
Variable lease expense	1	1
Finance lease expense
Amortization of leased assets	0
Interest on lease liabilities	0	0
Total finance lease expense		0
Total lease expense	$ 8	$ 6