Regulatory Matters (Regulatory Matters Narrative - Piedmont) (Details) - Piedmont - 2024 North Carolina Rate Case - NCUC - Subsequent event $ in Millions	Apr. 01, 2024 USD ($)
Public Utilities, General Disclosures [Line Items]
Requested rate increase (decrease), amount	$ 159
Requested rate increase, percentage, net of tax	12.50%
Requested return on equity (as a percent)	10.50%
Equity ratio (as a percent)	53.00%
Percentage of additions covered under IMR mechanism	40.00%