Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Offsetting Assets [Line Items]
Gross amounts recognized	$ 57	$ 51
Net amounts presented on Balance Sheets	57	51
Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	38	35
Gross amounts offset	(3)
Net amounts presented on Balance Sheets	35	35
Other Noncurrent Assets [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	19	16
Gross amounts offset	(3)
Net amounts presented on Balance Sheets	16	16
Duke Energy Carolinas [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	3	2
Net amounts presented on Balance Sheets	3	2
Duke Energy Carolinas [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	2
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		2
Duke Energy Carolinas [Member] | Other Noncurrent Assets [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	1
Gross amounts offset	(1)
Progress Energy [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	4	3
Net amounts presented on Balance Sheets	4	3
Progress Energy [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	2
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		2
Progress Energy [Member] | Other Noncurrent Assets [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	1
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		1
Duke Energy Progress [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	4	2
Net amounts presented on Balance Sheets	4	2
Duke Energy Progress [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	1
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		1
Duke Energy Progress [Member] | Other Noncurrent Assets [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	1
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		1
Duke Energy Florida [Member]
Offsetting Assets [Line Items]
Gross amounts recognized		1
Net amounts presented on Balance Sheets		1
Duke Energy Florida [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized		1
Net amounts presented on Balance Sheets		1
Duke Energy Ohio [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	6	1
Net amounts presented on Balance Sheets	6	1
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	6	1
Net amounts presented on Balance Sheets	6	1
Duke Energy Indiana [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	23	27
Net amounts presented on Balance Sheets	23	27
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	23	27
Net amounts presented on Balance Sheets	23	27
Piedmont Natural Gas [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	3	2
Net amounts presented on Balance Sheets	3	2
Piedmont Natural Gas [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	3	2
Net amounts presented on Balance Sheets	$ 3	$ 2