Leases (Supplemental Financial Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Assets
Operating	$ 1,698	$ 1,750
Finance	1,081
Total lease assets	2,779
Current
Operating	183	205
Finance	121
Noncurrent
Operating	1,488	1,504
Finance	968
Total lease liabilities	2,760
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	67
Operating cash flows from finance leases	17
Financing cash flows from finance leases	27
Lease assets obtained in exchange for new lease liabilities (non-cash)
Finance	175
Operating(b)	$ 7
Weighted-average remaining lease term (years)
Operating leases	11 years
Finance leases	13 years
Weighted-average discount rate
Operating leases	3.90%
Finance leases	6.90%
Duke Energy Carolinas [Member]
Assets
Operating	$ 146	153
Finance	122
Total lease assets	268
Current
Operating	26	28
Finance	6
Noncurrent
Operating	123	127
Finance	102
Total lease liabilities	257
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	6
Operating cash flows from finance leases	4
Financing cash flows from finance leases	$ 1
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	$ 835	863
Finance	428
Total lease assets	1,263
Current
Operating	89	96
Finance	23
Noncurrent
Operating	748	766
Finance	400
Total lease liabilities	1,260
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	31
Operating cash flows from finance leases	6
Financing cash flows from finance leases	3
Lease assets obtained in exchange for new lease liabilities (non-cash)
Finance	$ 175
Weighted-average remaining lease term (years)
Operating leases	11 years
Finance leases	16 years
Weighted-average discount rate
Operating leases	3.80%
Finance leases	11.40%
Duke Energy Progress [Member]
Assets
Operating	$ 388	407
Finance	310
Total lease assets	698
Current
Operating	27	35
Finance	6
Noncurrent
Operating	361	371
Finance	305
Total lease liabilities	699
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	14
Operating cash flows from finance leases	4
Financing cash flows from finance leases	1
Lease assets obtained in exchange for new lease liabilities (non-cash)
Finance	$ 175
Weighted-average remaining lease term (years)
Operating leases	13 years
Finance leases	18 years
Weighted-average discount rate
Operating leases	3.90%
Finance leases	12.50%
Duke Energy Florida [Member]
Assets
Operating	$ 447	456
Finance	118
Total lease assets	565
Current
Operating	62	61
Finance	17
Noncurrent
Operating	387	395
Finance	95
Total lease liabilities	561
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	17
Operating cash flows from finance leases	2
Financing cash flows from finance leases	$ 2
Weighted-average remaining lease term (years)
Operating leases	9 years
Finance leases	11 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	1
Noncurrent
Operating	21	22
Total lease liabilities	23
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating 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	3.30%
Duke Energy Indiana [Member]
Assets
Operating	$ 61	61
Finance	10
Total lease assets	71
Current
Operating	4	4
Noncurrent
Operating	57	58
Finance	10
Total lease liabilities	71
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	$ 2
Weighted-average remaining lease term (years)
Operating leases	19 years
Finance leases	27 years
Weighted-average discount rate
Operating leases	4.10%
Finance leases	11.70%
Piedmont Natural Gas [Member]
Assets
Operating	$ 27	26
Total lease assets	27
Current
Operating	4	4
Noncurrent
Operating	26	$ 25
Total lease liabilities	30
Cash paid for amounts included in the measurement of lease liabilities(a)
Operating cash flows from operating leases	$ 2
Weighted-average remaining lease term (years)
Operating leases	7 years
Finance leases	0 years
Weighted-average discount rate
Operating leases	3.60%