Leases (Supplemental Financial Information) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jan. 01, 2019
Assets
Operating	$ 1,735	$ 1,750
Finance	1,013
Total lease assets	2,748
Current
Operating	213	205
Finance	115
Noncurrent
Operating	1,502	1,504
Finance	907
Total lease liabilities	2,737
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	136
Operating cash flows from finance leases	37
Financing cash flows from finance leases	56
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating	78
Finance	$ 175
Weighted-average remaining lease term (years)
Operating leases	11 years
Finance leases	16 years
Weighted-average discount rate
Operating leases	3.90%
Finance leases	7.90%
Duke Energy Carolinas [Member]
Assets
Operating	$ 141	153
Finance	122
Total lease assets	263
Current
Operating	27	28
Finance	6
Noncurrent
Operating	117	127
Finance	101
Total lease liabilities	251
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	15
Operating cash flows from finance leases	7
Financing cash flows from finance leases	2
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating	$ 2
Weighted-average remaining lease term (years)
Operating leases	9 years
Finance leases	19 years
Weighted-average discount rate
Operating leases	3.70%
Finance leases	12.90%
Progress Energy [Member]
Assets
Operating	$ 839	863
Finance	423
Total lease assets	1,262
Current
Operating	100	96
Finance	23
Noncurrent
Operating	747	766
Finance	394
Total lease liabilities	1,264
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	60
Operating cash flows from finance leases	19
Financing cash flows from finance leases	8
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating	30
Finance	$ 175
Weighted-average remaining lease term (years)
Operating leases	10 years
Finance leases	17 years
Weighted-average discount rate
Operating leases	3.80%
Finance leases	11.80%
Duke Energy Progress [Member]
Assets
Operating	$ 407	407
Finance	309
Total lease assets	716
Current
Operating	36	35
Finance	6
Noncurrent
Operating	377	371
Finance	304
Total lease liabilities	723
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	23
Operating cash flows from finance leases	14
Financing cash flows from finance leases	2
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating	30
Finance	$ 175
Weighted-average remaining lease term (years)
Operating leases	12 years
Finance leases	18 years
Weighted-average discount rate
Operating leases	3.80%
Finance leases	12.40%
Duke Energy Florida [Member]
Assets
Operating	$ 432	456
Finance	114
Total lease assets	546
Current
Operating	64	61
Finance	17
Noncurrent
Operating	370	395
Finance	90
Total lease liabilities	541
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	37
Operating cash flows from finance leases	5
Financing cash flows from finance leases	$ 6
Weighted-average remaining lease term (years)
Operating leases	9 years
Finance leases	12 years
Weighted-average discount rate
Operating leases	3.70%
Finance leases	8.30%
Duke Energy Ohio [Member]
Assets
Operating	$ 22	23
Total lease assets	22
Current
Operating	1	1
Finance	0
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	4.20%
Finance leases	0.00%
Duke Energy Indiana [Member]
Assets
Operating	$ 60	61
Finance	10
Total lease assets	70
Current
Operating	4	4
Noncurrent
Operating	56	58
Finance	10
Total lease liabilities	70
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	3
Operating cash flows from finance leases	$ 1
Weighted-average remaining lease term (years)
Operating leases	19 years
Finance leases	27 years
Weighted-average discount rate
Operating leases	4.10%
Finance leases	11.90%
Piedmont Natural Gas [Member]
Assets
Operating	$ 26	26
Total lease assets	26
Current
Operating	4	4
Noncurrent
Operating	25	$ 25
Total lease liabilities	29
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	5
Lease assets obtained in exchange for new lease liabilities (non-cash)
Operating	$ 1
Weighted-average remaining lease term (years)
Operating leases	6 years
Finance leases	0 years
Weighted-average discount rate
Operating leases	3.60%