Regulatory Matters (Tables)

3 Months Ended

Mar. 31, 2021

Regulated Operations [Abstract]

Schedule of Cost Recovery Clauses

The recovery balances for certain retail regulatory clauses of the traditional electric operating companies and Southern Company Gas at March 31, 2021 and December 31, 2020 were as follows:

Regulatory Clause	Balance Sheet Line Item	March 31, 2021		December 31, 2020
		(in millions)
Alabama Power
Rate CNP Compliance	Other regulatory liabilities, current	$	33	$	28
Rate CNP PPA	Other regulatory assets, deferred	58		58
Retail Energy Cost Recovery	Other regulatory liabilities, current	—		18
	Other regulatory assets, deferred	15		—
Natural Disaster Reserve	Other regulatory liabilities, deferred	52		77
Georgia Power
Fuel Cost Recovery	Over recovered fuel clause revenues	$	83	$	113
Mississippi Power
Fuel Cost Recovery	Over recovered regulatory clause liabilities	$	18	$	24
Ad Valorem Tax	Other regulatory assets, current	12		11
	Other regulatory assets, deferred	45		41
Property Damage Reserve	Other regulatory liabilities, deferred	—		4
	Other regulatory assets, deferred	1		—
Southern Company Gas
Natural Gas Cost Recovery(*)	Other regulatory liabilities	$	12	$	88
	Natural gas cost under recovery	487		—
	Other regulatory assets, deferred	185		—

(*)The significant change during the three months ended March 31, 2021 was primarily driven by an increase in the cost of gas purchased in February 2021 resulting from Winter Storm Uri.

Nuclear Construction Cost and Schedule

Georgia Power's approximate proportionate share of the remaining estimated capital cost to complete Plant Vogtle Units 3 and 4 by December 2021 and November 2022, respectively, is as follows:

	(in millions)
Base project capital cost forecast(a)(b)	$	8,619
Construction contingency estimate	136
Total project capital cost forecast(a)(b)	8,755
Net investment as of March 31, 2021(b)	(7,560)
Remaining estimate to complete(a)	$	1,195

(a)    Excludes financing costs expected to be capitalized through AFUDC of approximately $250 million, of which $118 million had been accrued through March 31, 2021.

(b)    Net of $1.7 billion received from Toshiba under the Guarantee Settlement Agreement and approximately $188 million in related customer refunds.

Schedule of Infrastructure Replacement Programs and Capital Projects

Capital expenditures incurred under specific infrastructure replacement programs during the first three months of 2021 were as follows:

Utility	Program	Three Months Ended March 31, 2021
		(in millions)
Nicor Gas	Investing in Illinois	$	45
Virginia Natural Gas	Steps to Advance Virginia's Energy	9
Total		$	54