Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Offsetting Liabilities [Line Items]
Gross amounts recognized	$ 324	$ 300
Net amounts presented on Balance Sheets	324	277
Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	64	118
Gross amounts offset	(3)	(24)
Net amounts presented on Balance Sheets	61	94
Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	260	182
Gross amounts offset	(5)
Net amounts presented on Balance Sheets	255	182
Duke Energy Carolinas
Offsetting Liabilities [Line Items]
Gross amounts recognized	20	49
Net amounts presented on Balance Sheets	20	49
Duke Energy Carolinas | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	17	39
Gross amounts offset	(2)
Net amounts presented on Balance Sheets	15	39
Duke Energy Carolinas | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	3	10
Gross amounts offset	(1)
Net amounts presented on Balance Sheets	2	10
Progress Energy
Offsetting Liabilities [Line Items]
Gross amounts recognized	29	88
Net amounts presented on Balance Sheets	29	65
Progress Energy | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	2	51
Gross amounts offset	(2)	(24)
Net amounts presented on Balance Sheets		27
Progress Energy | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	27	37
Gross amounts offset	(4)
Net amounts presented on Balance Sheets	23	37
Duke Energy Progress
Offsetting Liabilities [Line Items]
Gross amounts recognized	14	49
Net amounts presented on Balance Sheets	14	49
Duke Energy Progress | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	2	27
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		27
Duke Energy Progress | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	12	22
Gross amounts offset	(4)
Net amounts presented on Balance Sheets	8	22
Duke Energy Florida
Offsetting Liabilities [Line Items]
Gross amounts recognized		24
Net amounts presented on Balance Sheets		1
Duke Energy Florida | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	0	24
Gross amounts offset	0	(24)
Net amounts presented on Balance Sheets	0
Duke Energy Florida | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	0
Gross amounts offset	0
Net amounts presented on Balance Sheets	0
Duke Energy Ohio
Offsetting Liabilities [Line Items]
Gross amounts recognized	6	6
Duke Energy Ohio | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	1	1
Gross amounts offset	0
Net amounts presented on Balance Sheets	1	1
Duke Energy Ohio | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	5	5
Gross amounts offset	0
Net amounts presented on Balance Sheets	5	5
Duke Energy Indiana
Offsetting Liabilities [Line Items]
Gross amounts recognized	1	1
Net amounts presented on Balance Sheets	1	1
Duke Energy Indiana | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	1	1
Gross amounts offset	0
Net amounts presented on Balance Sheets	1	1
Duke Energy Indiana | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	0
Gross amounts offset	0
Net amounts presented on Balance Sheets	0
Piedmont
Offsetting Liabilities [Line Items]
Gross amounts recognized	122	117
Net amounts presented on Balance Sheets	122	117
Piedmont | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	15	7
Gross amounts offset	0
Net amounts presented on Balance Sheets	15	7
Piedmont | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	107	110
Gross amounts offset	0
Net amounts presented on Balance Sheets	$ 107	$ 110