Investments in Debt and Equity Securities (All Debt and Equity Securities Through OCI and FV-NI - ASU 2016-01) (Details) - USD ($) $ in Millions	Jun. 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	$ 3,209	$ 2,458
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	40	131
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	8,030	7,075
Debt securities, available-for-sale	2,577
Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	3,076	2,402
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	3,153	2,421
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	39	126
Cash and cash equivalents	114	88
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	7,603	6,706
Equity Securities, FV-NI, Accumulated Unrealized Loss	36	95
Equity securities, FV-NI	5,178	4,475
Debt securities, available-for-sale	2,425	2,231
Other Classification [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	49	36
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	56	37
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	1	5
Cash and cash equivalents	49	22
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	427	369
Equity Securities, FV-NI, Accumulated Unrealized Loss		1
Equity securities, FV-NI	112	99
Debt securities, available-for-sale	315	270
Duke Energy Carolinas [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt securities, available-for-sale	1,120
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	1,671	1,309
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,711	1,316
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	12	74
Cash and cash equivalents	41	29
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	4,044	3,553
Equity Securities, FV-NI, Accumulated Unrealized Loss	9	54
Equity securities, FV-NI	2,883	2,484
Debt securities, available-for-sale	1,161	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	1,445	1,105
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	27	52
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,656	3,217
Debt securities, available-for-sale	1,241
Progress Energy [Member] | Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,405	1,093
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,442	1,105
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	27	52
Cash and cash equivalents	73	59
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,559	3,153
Equity Securities, FV-NI, Accumulated Unrealized Loss	27	41
Equity securities, FV-NI	2,295	1,991
Debt securities, available-for-sale	1,264	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	3
Cash and cash equivalents	47	17
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	97	64
Debt securities, available-for-sale	97	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	1,128	842
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	24	39
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	2,836	2,500
Debt securities, available-for-sale	906
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	1,092	833
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,128	842
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	24	39
Cash and cash equivalents	42	46
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	2,834	2,494
Equity Securities, FV-NI, Accumulated Unrealized Loss	24	30
Equity securities, FV-NI	1,886	1,588
Debt securities, available-for-sale	948	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	317	263
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	3	13
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	777	707
Debt securities, available-for-sale	335
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	313	260
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	314	263
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	3	13
Cash and cash equivalents	31	13
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	725	659
Equity Securities, FV-NI, Accumulated Unrealized Loss	3	11
Equity securities, FV-NI	409	403
Debt securities, available-for-sale	316	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	3
Cash and cash equivalents	2	1
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	52	48
Debt securities, available-for-sale	52	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	37	29
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	1	1
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	116	108
Equity securities, FV-NI	74	67
Debt securities, available-for-sale	42
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