Leases (Lease Costs) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease expense	$ 72
Short-term lease expense	7
Variable lease expense	11
Finance lease expense
Amortization of leased assets	27
Interest on lease liabilities	17
Total finance lease expense	44
Total lease expense	134
Duke Energy Carolinas [Member]
Lessee, Lease, Description [Line Items]
Operating lease expense	12
Short-term lease expense	2
Variable lease expense	8
Finance lease expense
Amortization of leased assets	1
Interest on lease liabilities	4
Total finance lease expense	5
Total lease expense	27
Progress Energy [Member]
Lessee, Lease, Description [Line Items]
Operating lease expense	42
Short-term lease expense	3
Variable lease expense	2
Finance lease expense
Amortization of leased assets	3
Interest on lease liabilities	6
Total finance lease expense	9
Total lease expense	56
Duke Energy Progress [Member]
Lessee, Lease, Description [Line Items]
Operating lease expense	19
Short-term lease expense	1
Variable lease expense	1
Finance lease expense
Amortization of leased assets	1
Interest on lease liabilities	4
Total finance lease expense	5
Total lease expense	26
Duke Energy Florida [Member]
Lessee, Lease, Description [Line Items]
Operating lease expense	23
Short-term lease expense	2
Variable lease expense	1
Finance lease expense
Amortization of leased assets	2
Interest on lease liabilities	2
Total finance lease expense	4
Total lease expense	30
Duke Energy Ohio [Member]
Lessee, Lease, Description [Line Items]
Operating lease expense	3
Finance lease expense
Total lease expense	3
Duke Energy Indiana [Member]
Lessee, Lease, Description [Line Items]
Operating lease expense	5
Short-term lease expense	1
Finance lease expense
Total lease expense	6
Piedmont Natural Gas [Member]
Lessee, Lease, Description [Line Items]
Operating lease expense	1
Finance lease expense
Total lease expense	$ 1