Income Taxes (Other Disclosures) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	$ 25	$ 17	$ 88
Gross increases-tax positions in prior periods		12
Gross decreases-tax positions in prior periods	(2)	(4)	(4)
Gross increases-current period tax positions	7
Decreases due to settlements	(6)		(68)
Reduction due to lapse of statute of limitations			1
Total changes	(1)	8	(71)
Unrecognized Tax Benefits - December 31	24	25	17
Amount that if recognized, would affect the effective tax rate or regulatory liability	21
Amount that if recognized, would be recorded as a component of discontinued operations	2
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	2
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	3	5	4
Duke Energy Carolinas [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	5	1	72
Gross increases-tax positions in prior periods		4
Gross decreases-tax positions in prior periods	(1)		(4)
Gross increases-current period tax positions	2
Decreases due to settlements			(67)
Total changes	1	4	(71)
Unrecognized Tax Benefits - December 31	6	5	1
Amount that if recognized, would affect the effective tax rate or regulatory liability	6
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest expense recognized related to income taxes		2	7
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes		25	23
Progress Energy [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	5	2	1
Gross increases-tax positions in prior periods		3
Gross decreases-tax positions in prior periods			(1)
Gross increases-current period tax positions	4
Reduction due to lapse of statute of limitations			2
Total changes	4	3	1
Unrecognized Tax Benefits - December 31	9	5	2
Amount that if recognized, would affect the effective tax rate or regulatory liability	9
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	1	1	1
Duke Energy Progress [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	5	2	3
Gross increases-tax positions in prior periods		3
Gross decreases-tax positions in prior periods			(1)
Gross increases-current period tax positions	1
Total changes	1	3	(1)
Unrecognized Tax Benefits - December 31	6	5	2
Amount that if recognized, would affect the effective tax rate or regulatory liability	6
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	1	1	1
Duke Energy Florida [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	5	4
Gross increases-tax positions in prior periods		1	4
Gross decreases-tax positions in prior periods	(4)
Gross increases-current period tax positions	2
Total changes	(2)	1	4
Unrecognized Tax Benefits - December 31	3	5	4
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		1	2
Duke Energy Ohio [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	1	4
Gross increases-tax positions in prior periods		1	4
Gross decreases-tax positions in prior periods		(4)
Total changes		(3)	4
Unrecognized Tax Benefits - December 31	1	1	4
Amount that if recognized, would affect the effective tax rate or regulatory liability	1
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
Gross increases-tax positions in prior periods		1
Decreases due to settlements			(1)
Total changes		1	$ (1)
Unrecognized Tax Benefits - December 31	1	1
Amount that if recognized, would affect the effective tax rate or regulatory liability	1
Piedmont Natural Gas [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	3
Gross increases-tax positions in prior periods		3
Gross increases-current period tax positions	1
Total changes	1	3
Unrecognized Tax Benefits - December 31	4	$ 3
Amount that if recognized, would affect the effective tax rate or regulatory liability	$ 4
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes				$ 1