Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Offsetting Liabilities [Line Items]
Gross amounts recognized	$ 300	$ 242
Net amounts presented on Balance Sheets	277	242
Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	118	68
Gross amounts offset	(24)	(4)
Net amounts presented on Balance Sheets	94	64
Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	182	174
Gross amounts offset		(3)
Net amounts presented on Balance Sheets	182	171
Duke Energy Carolinas
Offsetting Liabilities [Line Items]
Gross amounts recognized	49	33
Net amounts presented on Balance Sheets	49	33
Duke Energy Carolinas | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	39	23
Gross amounts offset		(2)
Net amounts presented on Balance Sheets	39	21
Duke Energy Carolinas | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	10	10
Gross amounts offset		(1)
Net amounts presented on Balance Sheets	10	9
Progress Energy
Offsetting Liabilities [Line Items]
Gross amounts recognized	88	44
Net amounts presented on Balance Sheets	65	44
Progress Energy | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	51	23
Gross amounts offset	(24)	(2)
Net amounts presented on Balance Sheets	27	21
Progress Energy | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	37	21
Gross amounts offset		(2)
Net amounts presented on Balance Sheets	37	19
Duke Energy Progress
Offsetting Liabilities [Line Items]
Gross amounts recognized	49	27
Net amounts presented on Balance Sheets	49	27
Duke Energy Progress | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	27	16
Gross amounts offset		(2)
Net amounts presented on Balance Sheets	27	14
Duke Energy Progress | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	22	11
Gross amounts offset		(2)
Net amounts presented on Balance Sheets	22	9
Duke Energy Florida
Offsetting Liabilities [Line Items]
Gross amounts recognized	24	9
Net amounts presented on Balance Sheets	1	9
Duke Energy Florida | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	24	8
Gross amounts offset	(24)
Net amounts presented on Balance Sheets		8
Duke Energy Florida | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized		1
Net amounts presented on Balance Sheets		1
Duke Energy Ohio
Offsetting Liabilities [Line Items]
Gross amounts recognized	6	5
Duke Energy Ohio | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	1	1
Net amounts presented on Balance Sheets	1	1
Duke Energy Ohio | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	5	4
Net amounts presented on Balance Sheets	5	4
Duke Energy Indiana
Offsetting Liabilities [Line Items]
Gross amounts recognized	1
Net amounts presented on Balance Sheets	1
Duke Energy Indiana | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	1
Net amounts presented on Balance Sheets	1
Piedmont
Offsetting Liabilities [Line Items]
Gross amounts recognized	117	141
Net amounts presented on Balance Sheets	117	141
Piedmont | Current Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	7	8
Net amounts presented on Balance Sheets	7	8
Piedmont | Noncurrent Liabilities
Offsetting Liabilities [Line Items]
Gross amounts recognized	110	133
Net amounts presented on Balance Sheets	$ 110	$ 133