Debt and Credit Facilities (Summary of Debt and Related Terms) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unsecured Debt	$ 13,392	$ 12,937
Secured Debt	2,635	2,806
First mortgage bonds	18,980	19,180
Capital leases	1,336	1,428
Tax exempt bonds	1,053	1,296
Notes payable and commercial paper	4,258	2,989
Fair value hedge carrying value adjustment	6	8
Unamortized debt discount and premium, net	1,712	1,890
Unamortized debt issuance costs	(43)	(19)
Total debt	43,202	42,382
Short-term notes payable and commercial paper	(3,633)	(2,514)
Current maturities of long-term debt	(2,074)	(2,807)
Total long-term debt	37,495	37,061
Short term obligations classified as long-term debt	$ 972	$ 1,022
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument, Maturity Date Range, End	Dec. 31, 2073	Dec. 31, 2073
Weighted-average rate	4.99%	4.92%
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2016	Dec. 31, 2016
Debt Instrument, Maturity Date Range, End	Dec. 31, 2037	Dec. 31, 2037
Weighted-average rate	2.57%	2.50%
Short term obligations classified as long-term debt		$ 200
First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument, Maturity Date Range, End	Dec. 31, 2045	Dec. 31, 2044
Weighted-average rate	4.74%	4.76%
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument, Maturity Date Range, End	Dec. 31, 2051	Dec. 31, 2051
Weighted-average rate	5.38%	5.30%
Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2017	Dec. 31, 2015
Debt Instrument, Maturity Date Range, End	Dec. 31, 2041	Dec. 31, 2041
Weighted-average rate	2.59%	2.13%
Short term obligations classified as long-term debt	$ 347	$ 347
Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	625	475
Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Unamortized debt discount and premium, net	$ 1,798	$ 1,975
Notes Payable And Commercial Paper [Member]
Debt Instrument [Line Items]
Weighted-average rate	0.88%	0.70%
Short term obligations classified as long-term debt	$ 625	$ 475
TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (170)	$ (152)
Weighted-average rate	4.25%	4.29%
Parent Company [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 59
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Unsecured Debt	1,152	$ 1,155
Secured Debt	425	400
First mortgage bonds	6,161	6,161
Capital leases	24	27
Tax exempt bonds	355	355
Money pool borrowings	300	300
Fair value hedge carrying value adjustment	6	8
Unamortized debt discount and premium, net	(17)	(15)
Unamortized debt issuance costs	(4)	(4)
Total debt	8,367	8,353
Current maturities of long-term debt	(356)	(507)
Total long-term debt	8,011	7,846
Short term obligations classified as long-term debt	335	335
Duke Energy Carolinas [Member] | Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	35	35
Duke Energy Carolinas [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	300	300
Duke Energy Carolinas [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(39)	(38)
Progress Energy [Member]
Debt Instrument [Line Items]
Unsecured Debt	3,850	3,850
Secured Debt	479	525
First mortgage bonds	9,750	9,800
Capital leases	300	314
Tax exempt bonds	48	291
Money pool borrowings	1,458	835
Unamortized debt discount and premium, net	(28)	(26)
Unamortized debt issuance costs	(5)	(5)
Total debt	15,772	15,503
Short-term money pool borrowings	(1,308)	(835)
Current maturities of long-term debt	(315)	(1,507)
Total long-term debt	14,149	13,161
Progress Energy [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(85)	(86)
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Secured Debt	254	300
First mortgage bonds	5,975	5,475
Capital leases	144	146
Tax exempt bonds	48	291
Money pool borrowings	359
Unamortized debt discount and premium, net	(16)	(11)
Unamortized debt issuance costs	(3)	(3)
Total debt	6,727	6,170
Short-term money pool borrowings	(209)
Current maturities of long-term debt	(2)	(945)
Total long-term debt	6,516	5,225
Short term obligations classified as long-term debt	150
Duke Energy Progress [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	150
Duke Energy Progress [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Capital leases	114	129
Duke Energy Progress [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(37)	(31)
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Unsecured Debt	150	150
Secured Debt	225	225
First mortgage bonds	3,775	4,325
Capital leases	156	168
Money pool borrowings	813	84
Unamortized debt discount and premium, net	(8)	(8)
Unamortized debt issuance costs	(2)	(2)
Total debt	5,079	4,907
Short-term money pool borrowings	(813)	(84)
Current maturities of long-term debt	(13)	(562)
Total long-term debt	4,253	4,261
Duke Energy Florida [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Capital leases	731	787
Duke Energy Florida [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(32)	(37)
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Unsecured Debt	765	773
First mortgage bonds	750	900
Capital leases	13	20
Tax exempt bonds	77	77
Money pool borrowings	128	516
Unamortized debt discount and premium, net	(28)	(29)
Unamortized debt issuance costs	(2)	(2)
Total debt	1,701	2,251
Short-term money pool borrowings	(103)	(491)
Current maturities of long-term debt	(106)	(157)
Total long-term debt	1,492	1,603
Short term obligations classified as long-term debt	52	52
Duke Energy Ohio [Member] | Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	27	27
Duke Energy Ohio [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	25	25
Duke Energy Ohio [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(4)	(6)
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Unsecured Debt	740	742
First mortgage bonds	2,319	2,319
Capital leases	14	16
Tax exempt bonds	572	573
Money pool borrowings	150	221
Unamortized debt discount and premium, net	(8)	(9)
Unamortized debt issuance costs	(2)	(2)
Total debt	3,768	3,840
Short-term money pool borrowings		(71)
Current maturities of long-term debt	(547)	(5)
Total long-term debt	3,221	3,764
Short term obligations classified as long-term debt	435	435
Duke Energy Indiana [Member] | Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	285	285
Duke Energy Indiana [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	150	150
Duke Energy Indiana [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (19)	$ (22)