Investments in Debt and Equity Securities (All Debt and Equity Securities Through OCI and FV-NI - ASU 2016-01) (Details) - USD ($) $ in Millions	Mar. 31, 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	$ 3,022	$ 2,458
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	76	131
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	7,785	7,075
Debt securities, available-for-sale	2,447
Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	2,923	2,402
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	2,971	2,421
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	74	126
Cash and cash equivalents	114	88
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	7,363	6,706
Equity Securities, FV-NI, Accumulated Unrealized Loss	65	95
Equity securities, FV-NI	5,061	4,475
Debt securities, available-for-sale	2,302	2,231
Other Classification [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	47	36
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	51	37
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	2	5
Cash and cash equivalents	51	22
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	422	369
Equity Securities, FV-NI, Accumulated Unrealized Loss		1
Equity securities, FV-NI	112	99
Debt securities, available-for-sale	310	270
Duke Energy Carolinas [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Debt securities, available-for-sale	1,065
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	1,593	1,309
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,615	1,316
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	43	74
Cash and cash equivalents	57	29
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,913	3,553
Equity Securities, FV-NI, Accumulated Unrealized Loss	37	54
Equity securities, FV-NI	2,791	2,484
Debt securities, available-for-sale	1,122	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	1,358	1,105
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	31	52
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,546	3,217
Debt securities, available-for-sale	1,172
Progress Energy [Member] | Ndtf [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,330	1,093
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,356	1,105
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	31	52
Cash and cash equivalents	57	59
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,450	3,153
Equity Securities, FV-NI, Accumulated Unrealized Loss	28	41
Equity securities, FV-NI	2,270	1,991
Debt securities, available-for-sale	1,180	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	2	0
Cash and cash equivalents	47	17
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	96	64
Debt securities, available-for-sale	96	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	1,042	842
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	22	39
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	2,741	2,500
Debt securities, available-for-sale	883
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	1,022	833
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	1,042	842
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	22	39
Cash and cash equivalents	43	46
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	2,738	2,494
Equity Securities, FV-NI, Accumulated Unrealized Loss	20	30
Equity securities, FV-NI	1,812	1,588
Debt securities, available-for-sale	926	906
Duke Energy Progress [Member] | Other Classification [Member]
Schedule Of Available For Sale Securities And Other Trading Assets [Line Items]
Cash and cash equivalents	3	6
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3	6
Debt securities, available-for-sale	3	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	316	263
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Loss	9	13
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	762	707
Debt securities, available-for-sale	289
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	308	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	9	13
Cash and cash equivalents	14	13
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	712	659
Equity Securities, FV-NI, Accumulated Unrealized Loss	8	11
Equity securities, FV-NI	458	403
Debt securities, available-for-sale	254	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	2
Cash and cash equivalents	1	1
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	50	48
Debt securities, available-for-sale	50	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	118	108
Equity securities, FV-NI	76	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	$ 76	$ 67