PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Tables)

6 Months Ended

Mar. 31, 2018

Defined Contribution Plan [Abstract]

Schedule of Net Periodic Cost

Net periodic postretirement benefit costs consisted of the following components:

	Three Months Ended March 31,						Six Months Ended March 31,
	2018			2017			2018			2017
Spire
Service cost – benefits earned during the period	$	2.4		$	2.7		$	4.7		$	5.5
Interest cost on accumulated postretirement benefit obligation	2.2			2.2			4.4			4.3
Expected return on plan assets	(3.5		)	(3.4		)	(7.0		)	(6.8		)
Amortization of prior service credit	(0.1		)	—			(0.1		)	—
Amortization of actuarial loss	0.2			0.6			0.4			1.2
Subtotal	1.2			2.1			2.4			4.2
Regulatory adjustment	—			(0.8		)	0.1			(1.6		)
Net postretirement benefit cost	$	1.2		$	1.3		$	2.5		$	2.6

Spire Missouri
Service cost – benefits earned during the period	$	2.3		$	2.6		$	4.5		$	5.2
Interest cost on accumulated postretirement benefit obligation	1.8			1.7			3.6			3.4
Expected return on plan assets	(2.5		)	(2.2		)	(4.9		)	(4.5		)
Amortization of prior service cost	—			—			0.1			0.1
Amortization of actuarial loss	0.2			0.7			0.4			1.3
Subtotal	1.8			2.8			3.7			5.5
Regulatory adjustment	0.5			(0.3		)	1.0			(0.7		)
Net postretirement benefit cost	$	2.3		$	2.5		$	4.7		$	4.8

Spire Alabama
Service cost – benefits earned during the period	$	0.1		$	0.1		$	0.1		$	0.2
Interest cost on accumulated postretirement benefit obligation	0.3			0.4			0.7			0.8
Expected return on plan assets	(1.0		)	(1.1		)	(2.0		)	(2.2		)
Amortization of prior service credit	(0.1		)	—			(0.2		)	(0.1		)
Amortization of actuarial gain	—			(0.1		)	—			(0.1		)
Subtotal	(0.7		)	(0.7		)	(1.4		)	(1.4		)
Regulatory adjustment	(0.5		)	(0.5		)	(0.9		)	(0.9		)
Net postretirement benefit income	$	(1.2	)	$	(1.2	)	$	(2.3	)	$	(2.3	)

The net periodic pension cost included the following components:

	Three Months Ended March 31,						Six Months Ended March 31,
	2018			2017			2018			2017
Spire
Service cost – benefits earned during the period	$	5.2		$	5.2		$	10.4		$	10.5
Interest cost on projected benefit obligation	6.9			6.9			13.8			13.8
Expected return on plan assets	(9.5		)	(9.7		)	(19.2		)	(19.6		)
Amortization of prior service (credit) cost	(0.2		)	0.3			(0.5		)	0.5
Amortization of actuarial loss	2.9			3.2			6.0			6.6
Loss on lump-sum settlements	9.4			11.9			9.4			11.9
Subtotal	14.7			17.8			19.9			23.7
Regulatory adjustment	24.0			(7.4		)	28.3			(2.8		)
Net pension cost	$	38.7		$	10.4		$	48.2		$	20.9

Spire Missouri
Service cost – benefits earned during the period	$	3.2		$	3.3		$	6.5		$	6.6
Interest cost on projected benefit obligation	4.9			4.9			9.8			9.7
Expected return on plan assets	(7.0		)	(7.1		)	(14.2		)	(14.4		)
Amortization of prior service cost	0.2			0.3			0.4			0.5
Amortization of actuarial loss	2.5			2.8			5.1			5.7
Loss on lump-sum settlements	9.4			11.5			9.4			11.5
Subtotal	13.2			15.7			17.0			19.6
Regulatory adjustment	21.9			(8.6		)	24.3			(5.8		)
Net pension cost	$	35.1		$	7.1		$	41.3		$	13.8

Spire Alabama
Service cost – benefits earned during the period	$	1.7		$	1.5		$	3.3		$	3.1
Interest cost on projected benefit obligation	1.4			1.5			2.8			3.0
Expected return on plan assets	(1.7		)	(1.8		)	(3.4		)	(3.6		)
Amortization of prior service credit	(0.4		)	—			(0.9		)	—
Amortization of actuarial loss	0.4			0.4			0.9			0.9
Loss on lump-sum settlements	—			0.4			—			0.4
Subtotal	1.4			2.0			2.7			3.8
Regulatory adjustment	1.9			1.1			3.6			2.7
Net pension cost	$	3.3		$	3.1		$	6.3		$	6.5