Leases (Operating Lease Right-of-use Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
ROU assets	$ 1,658	$ 1,750
Operating lease liabilities – current	208	205
Operating lease liabilities – noncurrent	1,432	1,504
Duke Energy Carolinas
Lessee, Lease, Description [Line Items]
ROU assets	123	153
Operating lease liabilities – current	27	28
Operating lease liabilities – noncurrent	102	127
Progress Energy
Lessee, Lease, Description [Line Items]
ROU assets	788	863
Operating lease liabilities – current	95	96
Operating lease liabilities – noncurrent	697	766
Duke Energy Progress
Lessee, Lease, Description [Line Items]
ROU assets	387	407
Operating lease liabilities – current	37	35
Operating lease liabilities – noncurrent	354	371
Duke Energy Florida
Lessee, Lease, Description [Line Items]
ROU assets	401	456
Operating lease liabilities – current	58	61
Operating lease liabilities – noncurrent	343	395
Duke Energy Ohio
Lessee, Lease, Description [Line Items]
ROU assets	21	23
Operating lease liabilities – current	1	1
Operating lease liabilities – noncurrent	21	22
Duke Energy Indiana
Lessee, Lease, Description [Line Items]
ROU assets	57	61
Operating lease liabilities – current	3	4
Operating lease liabilities – noncurrent	55	58
Piedmont
Lessee, Lease, Description [Line Items]
ROU assets	24	26
Operating lease liabilities – current	4	4
Operating lease liabilities – noncurrent	$ 23	$ 25