Regulatory Matters - GPC Nuclear Construction Cost and Schedule (Details) - GEORGIA POWER CO - Plant Vogtle Units 3 And 4 $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Loss Contingencies [Line Items]
Base project capital cost forecast	$ 9,342
Construction contingency estimate	137
Total project capital cost forecast	9,479
Net investment as of end of the period	(8,159)
Remaining estimate to complete	1,320
Estimated cost to complete, costs not shared with other owners	570
Expected capitalized costs	318
Capitalized interest accrued	169
Twenty Fourth Vogtle Construction Monitoring Report
Loss Contingencies [Line Items]
Guarantor obligations	1,700
Customer refund	$ 188