Leases (Supplemental Financial Information) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Jan. 01, 2019
Assets
Operating	$ 1,703	$ 1,750
Finance	952
Total lease assets	2,655
Current
Operating	212	205
Finance	117
Noncurrent
Operating	1,456	1,504
Finance	873
Total lease liabilities	2,658
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	221
Operating cash flows from finance leases	44
Financing cash flows from finance leases	84
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating, lease assets obtained	147
Finance	$ 175
Weighted-average remaining lease term (years)
Operating leases	11 years
Finance leases	13 years
Weighted-average discount rate
Operating leases	3.90%
Finance leases	8.00%
Duke Energy Carolinas [Member]
Assets
Operating	$ 135	153
Finance	125
Total lease assets	260
Current
Operating	27	28
Finance	6
Noncurrent
Operating	108	127
Finance	100
Total lease liabilities	241
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	26
Operating cash flows from finance leases	10
Financing cash flows from finance leases	4
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating, lease assets obtained	$ 44
Weighted-average remaining lease term (years)
Operating leases	9 years
Finance leases	18 years
Weighted-average discount rate
Operating leases	3.50%
Finance leases	12.90%
Progress Energy [Member]
Assets
Operating	$ 814	863
Finance	448
Total lease assets	1,262
Current
Operating	99	96
Finance	23
Noncurrent
Operating	710	766
Finance	385
Total lease liabilities	1,217
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	104
Operating cash flows from finance leases	31
Financing cash flows from finance leases	17
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating, lease assets obtained	30
Finance	$ 175
Weighted-average remaining lease term (years)
Operating leases	10 years
Finance leases	16 years
Weighted-average discount rate
Operating leases	3.80%
Finance leases	11.80%
Duke Energy Progress [Member]
Assets
Operating	$ 397	407
Finance	309
Total lease assets	706
Current
Operating	36	35
Finance	6
Noncurrent
Operating	360	371
Finance	302
Total lease liabilities	704
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	43
Operating cash flows from finance leases	24
Financing cash flows from finance leases	3
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating, lease assets obtained	30
Finance	$ 175
Weighted-average remaining lease term (years)
Operating leases	12 years
Finance leases	18 years
Weighted-average discount rate
Operating leases	3.90%
Finance leases	12.40%
Duke Energy Florida [Member]
Assets
Operating	$ 417	456
Finance	139
Total lease assets	556
Current
Operating	63	61
Finance	17
Noncurrent
Operating	350	395
Finance	83
Total lease liabilities	513
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	61
Operating cash flows from finance leases	7
Financing cash flows from finance leases	$ 14
Weighted-average remaining lease term (years)
Operating leases	8 years
Finance leases	11 years
Weighted-average discount rate
Operating leases	3.80%
Finance leases	8.30%
Duke Energy Ohio [Member]
Assets
Operating	$ 22	23
Total lease assets	22
Current
Operating	1	1
Noncurrent
Operating	21	22
Total lease liabilities	22
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	1
Financing cash flows from finance leases	$ 1
Weighted-average remaining lease term (years)
Operating leases	18 years
Finance leases	0 years
Weighted-average discount rate
Operating leases	4.30%
Duke Energy Indiana [Member]
Assets
Operating	$ 58	61
Finance	10
Total lease assets	68
Current
Operating	3	4
Noncurrent
Operating	55	58
Finance	10
Total lease liabilities	68
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	5
Operating cash flows from finance leases	$ 1
Weighted-average remaining lease term (years)
Operating leases	18 years
Finance leases	27 years
Weighted-average discount rate
Operating leases	4.10%
Finance leases	11.90%
Piedmont Natural Gas [Member]
Assets
Operating	$ 25	26
Total lease assets	25
Current
Operating	4	4
Noncurrent
Operating	24	$ 25
Total lease liabilities	28
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	6
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating, lease assets obtained	$ 1
Weighted-average remaining lease term (years)
Operating leases	6 years
Finance leases	0 years
Weighted-average discount rate
Operating leases	3.60%