Utility Plant and Nonutility Property (Narrative) (Details) - Summer $ in Millions	1 Months Ended
	May 31, 2019 USD ($)
Utility Plant And Non Utility Property [Line Items]
Percentage of ownership interest	66.70%
NND Project
Utility Plant And Non Utility Property [Line Items]
Percentage of ownership interest	55.00%
Santee Cooper | NND Project
Utility Plant And Non Utility Property [Line Items]
Percentage of ownership interest	11.70%
Ownership interest purchased	$ 8