Regulatory Matters (Tables)

12 Months Ended

Sep. 30, 2021

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, 2021 and 2020.

	Spire				Spire Missouri				Spire Alabama
September 30	2021		2020		2021		2020		2021		2020
Regulatory Assets:
Current:
Pension and postretirement benefit costs	$	31.1	$	30.6	$	21.9	$	21.9	$	8.2	$	7.7
Unamortized purchased gas adjustments		243.5		5.5		242.8		—		—		5.5
Other		31.9		33.4		11.6		10.2		10.6		7.2
Total Current Regulatory Assets		306.5		69.5		276.3		32.1		18.8		20.4
Noncurrent:
Future income taxes due from customers		132.9		123.5		124.2		114.6		2.2		2.2
Pension and postretirement benefit costs		313.8		439.3		226.0		332.6		82.9		98.2
Cost of removal		431.9		395.6		34.9		7.1		397.0		388.6
Unamortized purchased gas adjustments		—		12.1		—		12.1		—		—
Energy efficiency		47.6		39.6		47.6		39.6		—		—
Other		67.3		59.3		50.4		42.7		1.2		0.9
Total Noncurrent Regulatory Assets		993.5		1,069.4		483.1		548.7		483.3		489.9
Total Regulatory Assets	$	1,300.0	$	1,138.9	$	759.4	$	580.8	$	502.1	$	510.3
Regulatory Liabilities:
Current:
Pension and postretirement benefit costs	$	5.8	$	5.8	$	3.6	$	3.6	$	2.2	$	2.2
Unamortized purchased gas adjustments		11.0		73.1		—		72.3		10.2		—
Other		17.8		34.1		13.5		27.3		1.0		1.7
Total Current Regulatory Liabilities		34.6		113.0		17.1		103.2		13.4		3.9
Noncurrent:
Deferred taxes due to customers		127.5		138.8		110.2		121.4		—		—
Pension and postretirement benefit costs		159.3		157.6		131.4		140.4		19.8		14.8
Accrued cost of removal		36.2		28.6		4.9		—		—		—
Unamortized purchased gas adjustments		284.3		4.4		284.3		4.4		—		—
Other		13.6		14.3		8.0		8.6		3.6		3.7
Total Noncurrent Regulatory Liabilities		620.9		343.7		538.8		274.8		23.4		18.5
Total Regulatory Liabilities	$	655.5	$	456.7	$	555.9	$	378.0	$	36.8	$	22.4

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	2021		2020		2021		2020
Pension and postretirement benefit costs	$	165.7	$	232.3	$	165.7	$	232.3
Future income taxes due from customers		130.7		121.3		124.2		114.6
Unamortized purchase gas adjustments		242.8		—		242.8		—
Other		86.0		12.9		86.0		12.9
Total Regulatory Assets Not Earning a Return	$	625.2	$	366.5	$	618.7	$	359.8