Income Taxes (Other Disclosures) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	$ 213	$ 230	$ 540
Gross decreases-tax positions in prior periods	(48)	(2)	(231)
Decreases due to settlements	(45)	(15)	(66)
Reduction due to lapse of statute of limitations	(32)		(13)
Total changes	(125)	(17)	(310)
Unrecognized Tax Benefits - December 31	88	213	230
Significant change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit	65
Amount that if recognized, would affect the effective tax rate or regulatory liability	62
Amount that if recognized, would be recorded as a component of discontinued operations	4
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	12	6	2
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest receivable related to income taxes	3
Interest payable related to income taxes		13	27
Duke Energy Carolinas [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	160	171	271
Gross decreases-tax positions in prior periods	(45)		(100)
Decreases due to settlements	(43)	(11)
Total changes	(88)	(11)	(100)
Unrecognized Tax Benefits - December 31	72	160	171
Significant change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit	63
Amount that if recognized, would affect the effective tax rate or regulatory liability	54
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes			2
Net interest expense recognized related to income taxes	1	1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	14	13	8
Progress Energy [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	32	32	131
Gross increases-tax positions in prior periods	1	1
Gross decreases-tax positions in prior periods			(86)
Decreases due to settlements		(1)
Reduction due to lapse of statute of limitations	(32)		(13)
Total changes	(31)		(99)
Unrecognized Tax Benefits - December 31	1	32	32
Amount that if recognized, would affect the effective tax rate or regulatory liability	2
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	2	3	6
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes		5	10
Duke Energy Progress [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	23	22	67
Gross increases-tax positions in prior periods	1	1
Gross decreases-tax positions in prior periods			(45)
Reduction due to lapse of statute of limitations	(21)
Total changes	(20)	1	(45)
Unrecognized Tax Benefits - December 31	3	23	22
Amount that if recognized, would affect the effective tax rate or regulatory liability	3
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	2		7
Net interest expense recognized related to income taxes		1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	1	3	2
Duke Energy Florida [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	8	8	44
Gross decreases-tax positions in prior periods			(37)
Reduction due to lapse of statute of limitations	(8)		1
Total changes	(8)		(36)
Unrecognized Tax Benefits - December 31		8	8
Amount that if recognized, would affect the effective tax rate or regulatory liability	1
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	1	1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes		5	7
Duke Energy Ohio [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1			36
Gross decreases-tax positions in prior periods			(36)
Total changes			(36)
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes		4	4
Duke Energy Indiana [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	1	1	32
Gross decreases-tax positions in prior periods			(31)
Total changes			(31)
Unrecognized Tax Benefits - December 31	1	1	1
Amount that if recognized, would affect the effective tax rate or regulatory liability	2
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	1	4	$ 1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest receivable related to income taxes	$ 3	$ 2