Contingencies and Regulatory Matters - Nuclear Construction Cost and Schedule (Details) - GEORGIA POWER CO - USD ($) $ in Millions		6 Months Ended	12 Months Ended
	Apr. 03, 2018	Jun. 30, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Customer refund	$ 330
Plant Vogtle Units 3 And 4
Loss Contingencies [Line Items]
Base project capital cost forecast		$ 8,000
Construction contingency estimate		400
Project capital cost forecast		8,400
Net investment as of June 30, 2018		(4,000)
Remaining estimate to complete		4,400
Expected capitalized costs		$ 350
Guarantor obligations			$ 1,700
Customer refund			$ 188