Investments in Debt and Equity Securities (All Debt and Equity Securities Through OCI and FV-NI - ASU 2016-01) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	$ 3,274	$ 2,458
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	64	131
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	8,134	7,075
Debt securities, available-for-sale	2,633
Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	3,118	2,402
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	3,215	2,421
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	64	126
Cash and cash equivalents	114	88
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	7,698	6,706
Equity Securities, FV-NI, Accumulated Unrealized Loss	63	95
Equity securities, FV-NI	5,222	4,475
Debt securities, available-for-sale	2,476	2,231
Other Classification [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	48	36
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	59	37
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss		5
Cash and cash equivalents	53	22
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	436	369
Equity Securities, FV-NI, Accumulated Unrealized Loss		1
Equity securities, FV-NI	112	99
Debt securities, available-for-sale	324	270
Duke Energy Carolinas [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt securities, available-for-sale	1,159
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,680	1,309
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,731	1,316
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	16	74
Cash and cash equivalents	36	29
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	4,096	3,553
Equity Securities, FV-NI, Accumulated Unrealized Loss	15	54
Equity securities, FV-NI	2,901	2,484
Debt securities, available-for-sale	1,195	1,069
Progress Energy [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,488	1,105
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	48	52
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,703	3,217
Debt securities, available-for-sale	1,255
Progress Energy [Member] | Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,438	1,093
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,484	1,105
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	48	52
Cash and cash equivalents	78	59
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,602	3,153
Equity Securities, FV-NI, Accumulated Unrealized Loss	48	41
Equity securities, FV-NI	2,321	1,991
Debt securities, available-for-sale	1,281	1,162
Progress Energy [Member] | Other Classification [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	4
Cash and cash equivalents	49	17
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	101	64
Debt securities, available-for-sale	101	64
Duke Energy Progress [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,152	842
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	30	39
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	2,884	2,500
Debt securities, available-for-sale	923
Duke Energy Progress [Member] | Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,107	833
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,152	842
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	30	39
Cash and cash equivalents	52	46
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	2,882	2,494
Equity Securities, FV-NI, Accumulated Unrealized Loss	30	30
Equity securities, FV-NI	1,907	1,588
Debt securities, available-for-sale	975	906
Duke Energy Progress [Member] | Other Classification [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Cash and cash equivalents	2	6
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	2	6
Debt securities, available-for-sale	2	6
Duke Energy Florida [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	336	263
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	18	13
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	776	707
Debt securities, available-for-sale	332
Duke Energy Florida [Member] | Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	331	260
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	332	263
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	18	13
Cash and cash equivalents	26	13
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	720	659
Equity Securities, FV-NI, Accumulated Unrealized Loss	18	11
Equity securities, FV-NI	414	403
Debt securities, available-for-sale	306	256
Duke Energy Florida [Member] | Other Classification [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	4
Cash and cash equivalents	4	1
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	56	48
Debt securities, available-for-sale	56	48
Duke Energy Indiana [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	37	29
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	38	29
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss		1
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	117	108
Equity securities, FV-NI	74	67
Debt securities, available-for-sale	43
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity securities, FV-NI	$ 74	$ 67