Components of the net periodic benefit costs for the three and six months ended June 30, 2018 and 2017 are presented in the following tables.



Three Months Ended June 30, 2018	Southern Company			Alabama Power			Georgia Power			Gulf Power			Mississippi Power			Southern Power			Southern Company Gas
	(in millions)
Pension Plans
Service cost	$	89		$	20		$	21		$	4		$	4		$	2		$	8
Interest cost	116			25			35			5			5			2			9
Expected return on plan assets	(235		)	(53		)	(74		)	(10		)	(10		)	(2		)	(17		)
Amortization:
Prior service costs	1			1			1			—			—			—			—
Regulatory asset	—			—			—			—			—			—			4
Net (gain)/loss	54			13			17			3			2			—			3
Net periodic pension cost (income)	$	25		$	6		$	—		$	2		$	1		$	2		$	7
Postretirement Benefits
Service cost	$	6		$	2		$	1		$	1		$	1		$	—		$	—
Interest cost	18			4			7			—			1			—			3
Expected return on plan assets	(17		)	(7		)	(7		)	(1		)	(1		)	—			(2		)
Amortization:
Prior service costs	1			1			1			—			—			—			—
Regulatory asset	—			—			—			—			—			—			2
Net (gain)/loss	4			1			2			—			—			—			—
Net periodic postretirement benefit cost	$	12		$	1		$	4		$	—		$	1		$	—		$	3



Six Months Ended June 30, 2018	Southern Company			Alabama Power			Georgia Power			Gulf Power			Mississippi Power			Southern Power			Southern Company Gas
	(in millions)
Pension Plans
Service cost	$	179		$	39		$	43		$	8		$	8		$	4		$	16
Interest cost	232			50			70			10			10			3			19
Expected return on plan assets	(471		)	(104		)	(148		)	(20		)	(20		)	(5		)	(35		)
Amortization:
Prior service costs	2			1			1			—			—			—			(1		)
Regulatory asset	—			—			—			—			—			—			7
Net (gain)/loss	107			27			34			5			5			1			6
Net periodic pension cost (income)	$	49		$	13		$	—		$	3		$	3		$	3		$	12
Postretirement Benefits
Service cost	$	12		$	3		$	3		$	1		$	1		$	—		$	1
Interest cost	37			8			14			1			2			—			5
Expected return on plan assets	(34		)	(13		)	(13		)	(1		)	(1		)	—			(4		)
Amortization:
Regulatory asset	3			2			1			—			—			—			3
Net (gain)/loss	7			1			4			—			—			—			—
Net periodic postretirement benefit cost	$	25		$	1		$	9		$	1		$	2		$	—		$	5



Three Months Ended June 30, 2017^(*)	Southern Company			Alabama Power			Georgia Power			Gulf Power			Mississippi Power			Southern Company Gas
	(in millions)
Pension Plans
Service cost	$	74		$	16		$	18		$	4		$	3		$	5
Interest cost	113			24			35			5			5			10
Expected return on plan assets	(225		)	(49		)	(70		)	(9		)	(10		)	(17		)
Amortization:
Prior service costs	3			—			1			—			1			(1		)
Net (gain)/loss	41			11			14			1			2			5
Net periodic pension cost (income)	$	6		$	2		$	(2	)	$	1		$	1		$	2
Postretirement Benefits
Service cost	$	6		$	2		$	1		$	1		$	1		$	—
Interest cost	20			4			8			—			1			2
Expected return on plan assets	(17		)	(8		)	(6		)	(1		)	(1		)	(1		)
Amortization:
Prior service costs	1			1			1			—			—			—
Net (gain)/loss	5			1			1			—			—			1
Net periodic postretirement benefit cost	$	15		$	—		$	5		$	—		$	1		$	2


(*)	Excludes Southern Power since Southern Power did not participate in the qualified pension and postretirement benefit plans until December 2017.



Six Months Ended June 30, 2017^(*)	Southern Company			Alabama Power			Georgia Power			Gulf Power			Mississippi Power			Southern Company Gas
	(in millions)
Pension Plans
Service cost	$	147		$	32		$	37		$	7		$	7		$	11
Interest cost	227			48			69			10			10			20
Expected return on plan assets	(449		)	(98		)	(141		)	(19		)	(20		)	(35		)
Amortization:
Prior service costs	6			1			2			—			1			(1		)
Net (gain)/loss	81			21			28			3			4			10
Net periodic pension cost (income)	$	12		$	4		$	(5	)	$	1		$	2		$	5
Postretirement Benefits
Service cost	$	12		$	3		$	3		$	1		$	1		$	1
Interest cost	40			9			15			1			2			5
Expected return on plan assets	(33		)	(14		)	(12		)	(1		)	(1		)	(3		)
Amortization:
Prior service costs	3			2			1			—			—			(1		)
Net (gain)/loss	7			1			3			—			—			2
Net periodic postretirement benefit cost	$	29		$	1		$	10		$	1		$	2		$	4


(*)	Excludes Southern Power since Southern Power did not participate in the qualified pension and postretirement benefit plans until December 2017.