Leases (Operating Lease Right-of-use Assets and Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
ROU assets	$ 1,735	$ 1,750
Operating lease liabilities – current	213	205
Operating lease liabilities – noncurrent	1,502	1,504
Duke Energy Carolinas [Member]
Lessee, Lease, Description [Line Items]
ROU assets	141	153
Operating lease liabilities – current	27	28
Operating lease liabilities – noncurrent	117	127
Progress Energy [Member]
Lessee, Lease, Description [Line Items]
ROU assets	839	863
Operating lease liabilities – current	100	96
Operating lease liabilities – noncurrent	747	766
Duke Energy Progress [Member]
Lessee, Lease, Description [Line Items]
ROU assets	407	407
Operating lease liabilities – current	36	35
Operating lease liabilities – noncurrent	377	371
Duke Energy Florida [Member]
Lessee, Lease, Description [Line Items]
ROU assets	432	456
Operating lease liabilities – current	64	61
Operating lease liabilities – noncurrent	370	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	60	61
Operating lease liabilities – current	4	4
Operating lease liabilities – noncurrent	56	58
Piedmont Natural Gas [Member]
Lessee, Lease, Description [Line Items]
ROU assets	26	26
Operating lease liabilities – current	4	4
Operating lease liabilities – noncurrent	$ 25	$ 25