Regulatory Matters - GPC Nuclear Construction Cost and Schedule (Details) - GEORGIA POWER CO - Plant Vogtle Units 3 And 4 - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Loss Contingencies [Line Items]
Base project capital cost forecast	$ 9,096
Construction contingency estimate	119
Total project capital cost forecast	9,215
Net investment as of end of the period	(7,856)
Remaining estimate to complete	1,359
Estimated cost to complete, costs not shared with other owners	570
Expected capitalized costs	290
Capitalized interest accrued	143
Twenty Third Vogtle Construction Monitoring Report
Loss Contingencies [Line Items]
Guarantor obligations	1,700	$ 1,700
Customer refund	$ 188	$ 188