Introduction - Nuclear Decommissioning (Details) - ALABAMA POWER CO - Plant Farley $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Beginning year	2037
Completion year	2076
Site study costs	$ 1,720
Radiated structures
Public Utility, Property, Plant and Equipment [Line Items]
Site study costs	1,621
Non-radiated structures
Public Utility, Property, Plant and Equipment [Line Items]
Site study costs	$ 99