Retirement Benefits (Tables)

9 Months Ended

Sep. 30, 2022

Retirement Benefits [Abstract]

Schedule of Pension Plans and Postretirement Plans

Components of the net periodic benefit costs for the three and nine months ended September 30, 2022 and 2021 are presented in the following tables.

	Southern Company		Alabama Power		Georgia Power		Mississippi Power		Southern Power		Southern Company Gas
	(in millions)
Three Months Ended September 30, 2022
Pension Plans
Service cost	$	103	$	25	$	26	$	5	$	2	$	9
Interest cost	102		24		31		5		2		7
Expected return on plan assets	(316)		(77)		(99)		(15)		(4)		(22)
Amortization:
Prior service costs	—		—		—		—		—		(1)
Regulatory asset	—		—		—		—		—		3
Net loss	60		16		18		2		1		2
Net periodic pension cost (income)	$	(51)	$	(12)	$	(24)	$	(3)	$	1	$	(2)
Postretirement Benefits
Service cost	$	6	$	2	$	2	$	1	$	1	$	—
Interest cost	10		3		4		—		—		1
Expected return on plan assets	(20)		(9)		(8)		—		—		(2)
Amortization:
Prior service costs	(1)		—		—		—		—		—
Regulatory asset	—		—		—		—		—		2
Net (gain)/loss	1		—		—		—		—		(1)
Net periodic postretirement benefit cost (income)	$	(4)	$	(4)	$	(2)	$	1	$	1	$	—
Nine Months Ended September 30, 2022
Pension Plans
Service cost	$	309	$	74	$	78	$	13	$	7	$	26
Interest cost	306		72		92		14		5		21
Expected return on plan assets	(949)		(229)		(298)		(44)		(12)		(68)
Amortization:
Prior service costs	—		—		1		—		—		(2)
Regulatory asset	—		—		—		—		—		11
Net loss	180		47		55		9		2		5
Net periodic pension cost (income)	$	(154)	$	(36)	$	(72)	$	(8)	$	2	$	(7)
Postretirement Benefits
Service cost	$	17	$	5	$	5	$	1	$	1	$	1
Interest cost	31		8		11		1		—		4
Expected return on plan assets	(60)		(25)		(21)		(1)		—		(6)
Amortization:
Prior service costs	(1)		—		—		—		—		—
Regulatory asset	—		—		—		—		—		5
Net (gain)/loss	1		—		1		—		—		(2)
Net periodic postretirement benefit cost (income)	$	(12)	$	(12)	$	(4)	$	1	$	1	$	2

	Southern Company		Alabama Power		Georgia Power		Mississippi Power		Southern Power		Southern Company Gas
	(in millions)
Three Months Ended September 30, 2021
Pension Plans
Service cost	$	109	$	26	$	28	$	4	$	2	$	10
Interest cost	87		20		26		4		2		6
Expected return on plan assets	(298)		(72)		(94)		(14)		(4)		(21)
Amortization:
Prior service costs	—		—		—		—		—		(1)
Regulatory asset	—		—		—		—		—		3
Net loss	78		21		25		4		1		3
Net periodic pension cost (income)	$	(24)	$	(5)	$	(15)	$	(2)	$	1	$	—
Postretirement Benefits
Service cost	$	6	$	2	$	2	$	1	$	1	$	—
Interest cost	9		2		3		—		—		1
Expected return on plan assets	(19)		(8)		(7)		(1)		—		(2)
Amortization:
Regulatory asset	—		—		—		—		—		2
Net (gain)/loss	1		—		1		—		—		(1)
Net periodic postretirement benefit cost (income)	$	(3)	$	(4)	$	(1)	$	—	$	1	$	—
Nine Months Ended September 30, 2021
Pension Plans
Service cost	$	326	$	77	$	84	$	13	$	7	$	28
Interest cost	260		61		78		12		4		18
Expected return on plan assets	(893)		(215)		(282)		(41)		(11)		(64)
Amortization:
Prior service costs	—		—		1		—		—		(2)
Regulatory asset	—		—		—		—		—		11
Net loss	235		62		75		11		3		9
Net periodic pension cost (income)	$	(72)	$	(15)	$	(44)	$	(5)	$	3	$	—
Postretirement Benefits
Service cost	$	18	$	5	$	5	$	1	$	1	$	1
Interest cost	26		6		9		1		—		3
Expected return on plan assets	(57)		(22)		(20)		(2)		—		(6)
Amortization:
Prior service costs	(1)		—		—		—		—		—
Regulatory asset	—		—		—		—		—		5
Net (gain)/loss	3		—		2		—		—		(2)
Net periodic postretirement benefit cost (income)	$	(11)	$	(11)	$	(4)	$	—	$	1	$	1