Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of Regulatory Asset		$ 5	$ 7	$ 8
Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		182
Service cost		174	159	147
Interest cost		299	328	335
Expected return on plan assets		(559)	(545)	(519)
Amortization of actuarial loss (gain)		132	146	134
Amortization of prior service cost (credit)		(32)	(24)	(17)
Settlement charge			12	3
Other			8	8
Net periodic costs		22	84	91
Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		2	2	2
Interest cost		12	13	14
Amortization of actuarial loss (gain)		8	8	8
Amortization of prior service cost (credit)		(2)	(2)	(1)
Net periodic costs		20	21	23
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		58
Service cost		56	48	48
Interest cost		72	79	86
Expected return on plan assets		(147)	(142)	(142)
Amortization of actuarial loss (gain)		29	31	33
Amortization of prior service cost (credit)		(8)	(8)	(8)
Other			2	2
Net periodic costs		4	10	19
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1	1
Interest cost			1	1
Amortization of actuarial loss (gain)				1
Net periodic costs		1	2	2
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		51
Service cost		49	45	42
Interest cost		94	100	106
Expected return on plan assets		(178)	(167)	(168)
Amortization of actuarial loss (gain)		44	52	51
Amortization of prior service cost (credit)		(3)	(3)	(3)
Other			2	3
Net periodic costs		8	29	31
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		4	5	5
Amortization of actuarial loss (gain)		2	2	1
Net periodic costs		6	7	6
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		29
Service cost		28	26	24
Interest cost		43	47	49
Expected return on plan assets		(85)	(82)	(82)
Amortization of actuarial loss (gain)		21	23	23
Amortization of prior service cost (credit)		(2)	(2)	(2)
Other			1	1
Net periodic costs		6	13	13
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		1	1	1
Amortization of actuarial loss (gain)		1	1	1
Net periodic costs		2	2	2
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		22
Service cost		21	19	19
Interest cost		50	53	55
Expected return on plan assets		(91)	(85)	(84)
Amortization of actuarial loss (gain)		23	29	29
Amortization of prior service cost (credit)		(1)	(1)	(1)
Other			1	1
Net periodic costs		3	16	19
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		2	2	2
Amortization of actuarial loss (gain)		1	1	1
Net periodic costs		3	3	3
Pension Plan [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of Regulatory Asset		2	3	4
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		5
Service cost		5	4	4
Interest cost		17	18	19
Expected return on plan assets		(28)	(27)	(27)
Amortization of actuarial loss (gain)		5	5	4
Amortization of prior service cost (credit)			(1)
Other				1
Net periodic costs		(1)	(1)	1
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		11
Service cost		10	9	9
Interest cost		23	26	28
Expected return on plan assets		(42)	(42)	(42)
Amortization of actuarial loss (gain)		10	12	11
Amortization of prior service cost (credit)		(2)	(2)	(1)
Other			1	1
Net periodic costs		0	4	6
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		7
Service cost	$ 2	7	10		$ 11
Interest cost	2	11	14		9
Expected return on plan assets	(4)	(22)	(24)		(24)
Amortization of actuarial loss (gain)	2	11	11		8
Amortization of prior service cost (credit)	(1)	(10)	(2)		(2)
Settlement charge	3		12
Other			1
Net periodic costs	$ 4	(3)	22		2
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			0
Interest cost			0
Settlement charge					1
Net periodic costs					1
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		6	4	3
Interest cost		28	34	35
Expected return on plan assets		(13)	(14)	(12)
Amortization of actuarial loss (gain)		6	10	6
Amortization of prior service cost (credit)		(19)	(115)	(141)
Curtailment credit			(30)
Net periodic costs		8	(111)	(109)
Amortization of Regulatory Asset		7	7	8
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1	1	1
Interest cost		7	8	8
Expected return on plan assets		(8)	(8)	(8)
Amortization of actuarial loss (gain)		3	(2)	(3)
Amortization of prior service cost (credit)		(5)	(10)	(14)
Curtailment credit			(4)
Net periodic costs		(2)	(15)	(16)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1		1
Interest cost		12	13	15
Amortization of actuarial loss (gain)		1	21	22
Amortization of prior service cost (credit)		(8)	(84)	(103)
Curtailment credit			(16)
Net periodic costs		6	(66)	(65)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		6	7	8
Amortization of actuarial loss (gain)		1	12	13
Amortization of prior service cost (credit)		(1)	(54)	(68)
Net periodic costs		6	(35)	(47)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1		1
Interest cost		6	6	7
Amortization of actuarial loss (gain)			9	9
Amortization of prior service cost (credit)		(7)	(30)	(35)
Curtailment credit			(16)
Net periodic costs		0	(31)	(18)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1
Interest cost		1	1	1
Amortization of actuarial loss (gain)			(2)	(2)
Amortization of prior service cost (credit)		(1)
Curtailment credit			(2)
Net periodic costs		1	(3)	(1)
Amortization of Regulatory Asset		2	2	2
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1
Interest cost		3	3	4
Expected return on plan assets			(1)	(1)
Amortization of actuarial loss (gain)		4	(1)	(1)
Amortization of prior service cost (credit)		(1)	(1)	(1)
Curtailment credit			(2)
Net periodic costs		7	(2)	$ 1
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1	1		1
Interest cost		1	1		1
Expected return on plan assets		(2)	(2)		(2)
Amortization of actuarial loss (gain)			1		1
Amortization of prior service cost (credit)		(2)	0
Net periodic costs		$ (2)	$ 1		$ 1