Regulatory Matters (Tables)

12 Months Ended

Sep. 30, 2020

Regulated Operations [Abstract]

Schedule of Regulatory Assets and Liabilities

The following regulatory assets and regulatory liabilities were reflected in the Balance Sheets as of September 30, 2020 and 2019.

	Spire				Spire Missouri				Spire Alabama
September 30	2020		2019		2020		2019		2020		2019
Regulatory Assets:
Current:
Pension and postretirement benefit costs	$	30.6	$	30.1	$	21.9	$	21.9	$	7.7	$	7.3
Unamortized purchased gas adjustments		5.5		18.2		—		—		5.5		17.7
Other		33.4		30.3		10.2		7.5		7.2		8.9
Total Current Regulatory Assets		69.5		78.6		32.1		29.4		20.4		33.9
Noncurrent:
Future income taxes due from customers		123.5		111.0		114.6		102.9		2.2		2.2
Pension and postretirement benefit costs		439.3		416.6		332.6		333.3		98.2		77.2
Cost of removal		395.6		150.9		7.1		—		388.6		150.9
Unamortized purchased gas adjustments		12.1		9.1		12.1		9.1		—		—
Energy efficiency		39.6		35.0		39.6		35.0		—		—
Other		59.3		45.0		42.7		27.2		0.9		0.9
Total Noncurrent Regulatory Assets		1,069.4		767.6		548.7		507.5		489.9		231.2
Total Regulatory Assets	$	1,138.9	$	846.2	$	580.8	$	536.9	$	510.3	$	265.1
Regulatory Liabilities:
Current:
Pension and postretirement benefit costs	$	5.8	$	5.8	$	3.6	$	3.6	$	2.2	$	2.2
Unamortized purchased gas adjustments		73.1		26.2		72.3		25.4		—		—
Other		34.1		28.8		27.3		23.3		1.7		1.2
Total Current Regulatory Liabilities		113.0		60.8		103.2		52.3		3.9		3.4
Noncurrent:
Deferred taxes due to customers		138.8		179.8		121.4		162.5		—		—
Pension and postretirement benefit costs		157.6		142.3		140.4		119.1		14.8		19.1
Accrued cost of removal		28.6		41.6		—		15.7		—		—
Unamortized purchased gas adjustments		4.4		—		4.4		—		—		—
Other		14.3		35.3		8.6		29.2		3.7		3.9
Total Noncurrent Regulatory Liabilities		343.7		399.0		274.8		326.5		18.5		23.0
Total Regulatory Liabilities	$	456.7	$	459.8	$	378.0	$	378.8	$	22.4	$	26.4

Schedule of Regulatory Assets Not Earning a Return

A portion of the Company’s regulatory assets are not earning a return and are shown in the schedule below:

	Spire				Spire Missouri
September 30	2020		2019		2020		2019
Pension and postretirement benefit costs	$	232.3	$	211.1	$	232.3	$	211.1
Future income taxes due from customers		121.3		108.8		114.6		102.9
Other		12.9		14.3		12.9		14.3
Total Regulatory Assets Not Earning a Return	$	366.5	$	334.2	$	359.8	$	328.3