Retirement Benefits (Tables)

6 Months Ended

Jun. 30, 2023

Retirement Benefits [Abstract]

Schedule of Pension Plans and Postretirement Plans

Components of the net periodic benefit costs for the three and six months ended June 30, 2023 and 2022 are presented in the following tables.

	Southern Company		Alabama Power		Georgia Power		Mississippi Power		Southern Power		Southern Company Gas
	(in millions)
Three Months Ended June 30, 2023
Pension Plans
Service cost	$	69	$	16	$	17	$	3	$	1	$	6
Interest cost	157		36		47		7		2		11
Expected return on plan assets	(308)		(74)		(96)		(14)		(4)		(22)
Amortization:
Prior service costs	—		—		1		—		—		(1)
Regulatory asset	—		—		—		—		—		4
Net (gain) loss	8		3		3		—		—		(1)
Net periodic pension income	$	(74)	$	(19)	$	(28)	$	(4)	$	(1)	$	(3)
Postretirement Benefits
Service cost	$	3	$	1	$	1	$	—	$	—	$	—
Interest cost	17		4		7		1		—		2
Expected return on plan assets	(20)		(9)		(8)		—		—		(2)
Amortization:
Prior service costs	1		—		—		—		—		—
Regulatory asset	—		—		—		—		—		2
Net gain	(3)		—		(1)		—		—		(1)
Net periodic postretirement benefit cost (income)	$	(2)	$	(4)	$	(1)	$	1	$	—	$	1
Six Months Ended June 30, 2023
Pension Plans
Service cost	$	138	$	32	$	34	$	6	$	3	$	12
Interest cost	313		72		95		14		4		21
Expected return on plan assets	(615)		(148)		(192)		(28)		(8)		(44)
Amortization:
Prior service costs	—		—		1		—		—		(1)
Regulatory asset	—		—		—		—		—		8
Net (gain) loss	16		5		6		—		—		(2)
Net periodic pension income	$	(148)	$	(39)	$	(56)	$	(8)	$	(1)	$	(6)
Postretirement Benefits
Service cost	$	7	$	2	$	2	$	—	$	—	$	—
Interest cost	35		8		13		2		—		4
Expected return on plan assets	(41)		(17)		(15)		(1)		—		(3)
Amortization:
Prior service costs	1		—		—		—		—		—
Regulatory asset	—		—		—		—		—		3
Net gain	(6)		(1)		(2)		—		—		(2)
Net periodic postretirement benefit cost (income)	$	(4)	$	(8)	$	(2)	$	1	$	—	$	2

	Southern Company		Alabama Power		Georgia Power		Mississippi Power		Southern Power		Southern Company Gas
	(in millions)
Three Months Ended June 30, 2022
Pension Plans
Service cost	$	103	$	24	$	26	$	4	$	3	$	8
Interest cost	102		24		30		4		1		7
Expected return on plan assets	(317)		(75)		(100)		(14)		(4)		(24)
Amortization:
Prior service costs	—		—		1		—		—		—
Regulatory asset	—		—		—		—		—		4
Net loss	60		15		19		4		—		1
Net periodic pension income	$	(52)	$	(12)	$	(24)	$	(2)	$	—	$	(4)
Postretirement Benefits
Service cost	$	5	$	2	$	1	$	—	$	—	$	—
Interest cost	11		2		3		1		—		1
Expected return on plan assets	(20)		(8)		(6)		(1)		—		(1)
Amortization:
Regulatory asset	—		—		—		—		—		1
Net loss	—		—		1		—		—		—
Net periodic postretirement benefit cost (income)	$	(4)	$	(4)	$	(1)	$	—	$	—	$	1
Six Months Ended June 30, 2022
Pension Plans
Service cost	$	206	$	49	$	52	$	8	$	5	$	17
Interest cost	204		48		61		9		3		14
Expected return on plan assets	(633)		(152)		(199)		(29)		(8)		(46)
Amortization:
Prior service costs	—		—		1		—		—		(1)
Regulatory asset	—		—		—		—		—		8
Net loss	120		31		37		7		1		3
Net periodic pension cost (income)	$	(103)	$	(24)	$	(48)	$	(5)	$	1	$	(5)
Postretirement Benefits
Service cost	$	11	$	3	$	3	$	—	$	—	$	1
Interest cost	21		5		7		1		—		2
Expected return on plan assets	(40)		(16)		(13)		(1)		—		(3)
Amortization:
Regulatory asset	—		—		—		—		—		3
Net (gain) loss	—		—		1		—		—		(1)
Net periodic postretirement benefit cost (income)	$	(8)	$	(8)	$	(2)	$	—	$	—	$	2