Summary of Significant Accounting Policies (Inventory) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Public Utilities, Inventory [Line Items]
Materials and supplies	$ 2,397	$ 2,312
Coal	486	561
Natural gas, oil and other	316	294
Total inventory	3,199	3,167
Duke Energy Carolinas
Public Utilities, Inventory [Line Items]
Materials and supplies	793	785
Coal	195	186
Natural gas, oil and other	38	39
Total inventory	1,026	1,010
Progress Energy
Public Utilities, Inventory [Line Items]
Materials and supplies	1,067	999
Coal	167	193
Natural gas, oil and other	164	183
Total inventory	1,398	1,375
Duke Energy Progress
Public Utilities, Inventory [Line Items]
Materials and supplies	729	673
Coal	94	131
Natural gas, oil and other	98	107
Total inventory	921	911
Duke Energy Florida
Public Utilities, Inventory [Line Items]
Materials and supplies	338	325
Coal	73	63
Natural gas, oil and other	66	76
Total inventory	477	464
Duke Energy Ohio
Public Utilities, Inventory [Line Items]
Materials and supplies	80	78
Coal	19	16
Natural gas, oil and other	17	16
Total inventory	116	110
Duke Energy Indiana
Public Utilities, Inventory [Line Items]
Materials and supplies	311	307
Coal	105	165
Natural gas, oil and other	2	1
Total inventory	418	473
Piedmont
Public Utilities, Inventory [Line Items]
Materials and supplies	14	12
Natural gas, oil and other	95	56
Total inventory	$ 109	$ 68