Components of the net periodic benefit costs for the three months ended March 31, 2017 and 2016 are presented in the following tables.



Pension Plans	Southern Company			Alabama Power			Georgia Power			Gulf Power			Mississippi Power
	(in millions)
Three Months Ended March 31, 2017
Service cost	$	73		$	16		$	19		$	3		$	4
Interest cost	114			24			34			5			5
Expected return on plan assets	(224		)	(49		)	(71		)	(10		)	(10		)
Amortization:
Prior service costs	3			1			1			—			—
Net (gain)/loss	40			10			14			2			2
Net periodic pension cost (income)	$	6		$	2		$	(3	)	$	—		$	1
Three Months Ended March 31, 2016
Service cost	$	62		$	14		$	17		$	3		$	3
Interest cost	100			24			34			5			5
Expected return on plan assets	(187		)	(46		)	(64		)	(9		)	(9		)
Amortization:
Prior service costs	4			1			1			—			—
Net (gain)/loss	38			10			14			2			2
Net periodic pension cost	$	17		$	3		$	2		$	1		$	1



Pension Plans	Southern Company Gas
	(in millions)
Successor – Three Months Ended March 31, 2017
Service cost	$	6
Interest cost	10
Expected return on plan assets	(18		)
Amortization:
Prior service costs	—
Net (gain)/loss	5
Net periodic pension cost	$	3


Predecessor – Three Months Ended March 31, 2016
Service cost	$	6
Interest cost	10
Expected return on plan assets	(16		)
Amortization:
Prior service costs	—
Net (gain)/loss	6
Net periodic pension cost	$	6



Postretirement Benefits	Southern Company			Alabama Power			Georgia Power			Gulf Power		Mississippi Power
	(in millions)
Three Months Ended March 31, 2017
Service cost	$	6		$	1		$	2		$	—	$	—
Interest cost	20			5			7			1		1
Expected return on plan assets	(16		)	(6		)	(6		)	—		—
Amortization:
Prior service costs	2			1			—			—		—
Net (gain)/loss	2			—			2			—		—
Net periodic postretirement benefit cost	$	14		$	1		$	5		$	1	$	1
Three Months Ended March 31, 2016
Service cost	$	5		$	1		$	2		$	—	$	—
Interest cost	18			5			8			1		1
Expected return on plan assets	(14		)	(6		)	(6		)	—		—
Amortization:
Prior service costs	2			1			—			—		—
Net (gain)/loss	3			—			2			—		—
Net periodic postretirement benefit cost	$	14		$	1		$	6		$	1	$	1



Postretirement Benefits	Southern Company Gas
	(in millions)
Successor – Three Months Ended March 31, 2017
Service cost	$	1
Interest cost	3
Expected return on plan assets	(2		)
Amortization:
Prior service costs	(1		)
Net (gain)/loss	1
Net periodic postretirement benefit cost	$	2


Predecessor – Three Months Ended March 31, 2016
Service cost	$	1
Interest cost	3
Expected return on plan assets	(2		)
Amortization:
Prior service costs	(1		)
Net (gain)/loss	1
Net periodic postretirement benefit cost	$	2