Leases (Operating Lease Right-of-use Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
ROU assets	$ 1,703	$ 1,750
Operating lease liabilities – current	212	205
Operating lease liabilities – noncurrent	1,456	1,504
Duke Energy Carolinas [Member]
Lessee, Lease, Description [Line Items]
ROU assets	135	153
Operating lease liabilities – current	27	28
Operating lease liabilities – noncurrent	108	127
Progress Energy [Member]
Lessee, Lease, Description [Line Items]
ROU assets	814	863
Operating lease liabilities – current	99	96
Operating lease liabilities – noncurrent	710	766
Duke Energy Progress [Member]
Lessee, Lease, Description [Line Items]
ROU assets	397	407
Operating lease liabilities – current	36	35
Operating lease liabilities – noncurrent	360	371
Duke Energy Florida [Member]
Lessee, Lease, Description [Line Items]
ROU assets	417	456
Operating lease liabilities – current	63	61
Operating lease liabilities – noncurrent	350	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	58	61
Operating lease liabilities – current	3	4
Operating lease liabilities – noncurrent	55	58
Piedmont Natural Gas [Member]
Lessee, Lease, Description [Line Items]
ROU assets	25	26
Operating lease liabilities – current	4	4
Operating lease liabilities – noncurrent	$ 24	$ 25