Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [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]
Debt Securities, Available-for-sale [Line Items]
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
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	7,363	6,706
Debt securities, available-for-sale	2,302	2,231
Equity Securities, FV-NI, Accumulated Unrealized Gain	2,923	2,402
Equity Securities, FV-NI, Accumulated Unrealized Loss	65	95
Cash and cash equivalents	114	88
Equity securities, FV-NI	5,061	4,475
Ndtf [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	17	4
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	2	13
Debt securities, available-for-sale	624	566
Ndtf [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	5	1
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	4
Debt securities, available-for-sale	317	353
Ndtf [Member] | US treasury and government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	25	14
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	5	12
Debt securities, available-for-sale	1,102	1,076
Ndtf [Member] | Other debt obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	1
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	2
Debt securities, available-for-sale	145	148
Other Classification [Member]
Debt Securities, Available-for-sale [Line Items]
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
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	422	369
Debt securities, available-for-sale	310	270
Equity Securities, FV-NI, Accumulated Unrealized Gain	47	36
Equity Securities, FV-NI, Accumulated Unrealized Loss		1
Cash and cash equivalents	51	22
Equity securities, FV-NI	112	99
Other Classification [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	1
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax		2
Debt securities, available-for-sale	57	60
Other Classification [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	2	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	1
Debt securities, available-for-sale	89	85
Other Classification [Member] | US treasury and government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	1	1
Debt securities, available-for-sale	52	45
Other Classification [Member] | Other debt obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	1
Debt securities, available-for-sale	61	58
Duke Energy Carolinas [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	1,065
Duke Energy Carolinas [Member] | Ndtf [Member]
Debt Securities, Available-for-sale [Line Items]
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
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,913	3,553
Debt securities, available-for-sale	1,122	1,069
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,593	1,309
Equity Securities, FV-NI, Accumulated Unrealized Loss	37	54
Cash and cash equivalents	57	29
Equity securities, FV-NI	2,791	2,484
Duke Energy Carolinas [Member] | Ndtf [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	9	2
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	2	9
Debt securities, available-for-sale	354	341
Duke Energy Carolinas [Member] | Ndtf [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	1	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	1
Debt securities, available-for-sale	62	81
Duke Energy Carolinas [Member] | Ndtf [Member] | US treasury and government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	11	5
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	3	8
Debt securities, available-for-sale	509	475
Duke Energy Carolinas [Member] | Ndtf [Member] | Other debt obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	1	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	2
Debt securities, available-for-sale	140	143
Progress Energy [Member]
Debt Securities, Available-for-sale [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]
Debt Securities, Available-for-sale [Line Items]
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
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3,450	3,153
Debt securities, available-for-sale	1,180	1,162
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,330	1,093
Equity Securities, FV-NI, Accumulated Unrealized Loss	28	41
Cash and cash equivalents	57	59
Equity securities, FV-NI	2,270	1,991
Progress Energy [Member] | Ndtf [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	8	2
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax		4
Debt securities, available-for-sale	270	225
Progress Energy [Member] | Ndtf [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	4	1
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	3
Debt securities, available-for-sale	255	272
Progress Energy [Member] | Ndtf [Member] | US treasury and government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	14	9
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	2	4
Debt securities, available-for-sale	593	601
Progress Energy [Member] | Ndtf [Member] | Other debt obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	5	5
Progress Energy [Member] | Other Classification [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	2	0
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	96	64
Debt securities, available-for-sale	96	64
Cash and cash equivalents	47	17
Progress Energy [Member] | Other Classification [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	2	0
Debt securities, available-for-sale	49	47
Duke Energy Progress [Member]
Debt Securities, Available-for-sale [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]
Debt Securities, Available-for-sale [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	2,738	2,494
Debt securities, available-for-sale	926	906
Equity Securities, FV-NI, Accumulated Unrealized Gain	1,022	833
Equity Securities, FV-NI, Accumulated Unrealized Loss	20	30
Cash and cash equivalents	43	46
Equity securities, FV-NI	1,812	1,588
Duke Energy Progress [Member] | Ndtf [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	6	2
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	3
Debt securities, available-for-sale	204	171
Duke Energy Progress [Member] | Ndtf [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	4	1
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	3
Debt securities, available-for-sale	254	271
Duke Energy Progress [Member] | Ndtf [Member] | US treasury and government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	10	6
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	3
Debt securities, available-for-sale	422	415
Duke Energy Progress [Member] | Ndtf [Member] | Other debt obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	0
Debt securities, available-for-sale	3	3
Duke Energy Progress [Member] | Other Classification [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	3	6
Debt securities, available-for-sale	3	6
Cash and cash equivalents	3	6
Duke Energy Florida [Member]
Debt Securities, Available-for-sale [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]
Debt Securities, Available-for-sale [Line Items]
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
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	712	659
Debt securities, available-for-sale	254	256
Equity Securities, FV-NI, Accumulated Unrealized Gain	308	260
Equity Securities, FV-NI, Accumulated Unrealized Loss	8	11
Cash and cash equivalents	14	13
Equity securities, FV-NI	458	403
Duke Energy Florida [Member] | Ndtf [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	2	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	1
Debt securities, available-for-sale	66	54
Duke Energy Florida [Member] | Ndtf [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	0
Debt securities, available-for-sale	1	1
Duke Energy Florida [Member] | Ndtf [Member] | US treasury and government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	4	3
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	1
Debt securities, available-for-sale	171	186
Duke Energy Florida [Member] | Ndtf [Member] | Other debt obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	0	0
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	0	0
Debt securities, available-for-sale	2	2
Duke Energy Florida [Member] | Other Classification [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, and Equity Securities, FV-NI, Unrealized Gain	2
Debt Securities, Available-for-sale, and Equity Securities, FV-NI	50	48
Debt securities, available-for-sale	50	48
Cash and cash equivalents	1	1
Duke Energy Florida [Member] | Other Classification [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized gain, before tax	2	0
Debt securities, available-for-sale	49	47
Duke Energy Indiana [Member]
Debt Securities, Available-for-sale [Line Items]
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
Debt securities, available-for-sale	42
Equity Securities, FV-NI, Accumulated Unrealized Gain	37	29
Equity securities, FV-NI	76	67
Duke Energy Indiana [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	7	8
Duke Energy Indiana [Member] | Municipal bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, accumulated gross unrealized loss, before tax	1	1
Debt securities, available-for-sale	34	33
Duke Energy Indiana [Member] | US treasury and government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	1	0
Duke Energy Indiana [Member] | Other Classification [Member]
Debt Securities, Available-for-sale [Line Items]
Equity securities, FV-NI	$ 76	$ 67