Leases (Operating Lease Right-of-use Assets and Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
ROU assets	$ 1,698	$ 1,750
Operating lease liabilities – current	183	205
Operating lease liabilities – noncurrent	1,488	1,504
Duke Energy Carolinas [Member]
Lessee, Lease, Description [Line Items]
ROU assets	146	153
Operating lease liabilities – current	26	28
Operating lease liabilities – noncurrent	123	127
Progress Energy [Member]
Lessee, Lease, Description [Line Items]
ROU assets	835	863
Operating lease liabilities – current	89	96
Operating lease liabilities – noncurrent	748	766
Duke Energy Progress [Member]
Lessee, Lease, Description [Line Items]
ROU assets	388	407
Operating lease liabilities – current	27	35
Operating lease liabilities – noncurrent	361	371
Duke Energy Florida [Member]
Lessee, Lease, Description [Line Items]
ROU assets	447	456
Operating lease liabilities – current	62	61
Operating lease liabilities – noncurrent	387	395
Duke Energy Ohio [Member]
Lessee, Lease, Description [Line Items]
ROU assets	22	23
Operating lease liabilities – current	1	1
Operating lease liabilities – noncurrent	21	22
Duke Energy Indiana [Member]
Lessee, Lease, Description [Line Items]
ROU assets	61	61
Operating lease liabilities – current	4	4
Operating lease liabilities – noncurrent	57	58
Piedmont Natural Gas [Member]
Lessee, Lease, Description [Line Items]
ROU assets	27	26
Operating lease liabilities – current	4	4
Operating lease liabilities – noncurrent	$ 26	$ 25