Regulatory Matters - Schedule of Nuclear Construction Cost and Schedule (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments [Line Items]
Total AFUDC and interest capitalized	$ 210	$ 249	$ 327
Georgia Power
Commitments [Line Items]
Total AFUDC and interest capitalized	94	$ 63	$ 68
Maximum guarantee	30
Customer refund	40
Georgia Power | Plant Vogtle Units 3 And 4
Commitments [Line Items]
Base project capital cost forecast	8,000
Construction contingency estimate	400
Total project capital cost forecast	8,400
Net investment	(4,600)
Remaining estimate to complete	3,800
Total AFUDC and interest capitalized	315
Maximum guarantee	1,700
Customer refund	$ 188