Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Offsetting Liabilities [Line Items]
Gross amounts recognized	$ 242	$ 230
Net amounts presented on Balance Sheets	242	230
Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	68	66
Gross amounts offset	(4)	(3)
Net amounts presented on Balance Sheets	64	63
Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	174	164
Gross amounts offset	(3)	(1)
Net amounts presented on Balance Sheets	171	163
Duke Energy Carolinas [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	33	35
Net amounts presented on Balance Sheets	33	35
Duke Energy Carolinas [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	23	31
Gross amounts offset	(2)	(2)
Net amounts presented on Balance Sheets	21	29
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	10	4
Gross amounts offset	(1)
Net amounts presented on Balance Sheets	9	4
Progress Energy [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	44	36
Net amounts presented on Balance Sheets	44	36
Progress Energy [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	23	19
Gross amounts offset	(2)	(2)
Net amounts presented on Balance Sheets	21	17
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	21	17
Gross amounts offset	(2)	(1)
Net amounts presented on Balance Sheets	19	16
Duke Energy Progress [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	27	18
Net amounts presented on Balance Sheets	27	18
Duke Energy Progress [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	16	8
Gross amounts offset	(2)	(2)
Net amounts presented on Balance Sheets	14	6
Duke Energy Progress [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	11	10
Gross amounts offset	(2)	(1)
Net amounts presented on Balance Sheets	9	9
Duke Energy Florida [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	9	12
Net amounts presented on Balance Sheets	9	12
Duke Energy Florida [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	8	10
Net amounts presented on Balance Sheets	8	10
Duke Energy Florida [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	1	2
Net amounts presented on Balance Sheets	1	2
Duke Energy Ohio [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	5	5
Net amounts presented on Balance Sheets	5	5
Duke Energy Ohio [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	1	1
Net amounts presented on Balance Sheets	1	1
Duke Energy Ohio [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	4	4
Net amounts presented on Balance Sheets	4	4
Piedmont Natural Gas [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	141	142
Net amounts presented on Balance Sheets	141	142
Piedmont Natural Gas [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	8	11
Net amounts presented on Balance Sheets	8	11
Piedmont Natural Gas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	133	131
Net amounts presented on Balance Sheets	$ 133	$ 131