CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Net Income	$ 271.7	$ 88.6	$ 184.6
Cash flow hedging derivative instruments:
Net hedging gain (loss) arising during the period	61.2	(8.9)	(46.4)
Amounts reclassified into net income	(1.3)	(3.2)	(1.3)
Net gain (loss) on cash flow hedging derivative instruments	59.9	(12.1)	(47.7)
Net loss on defined benefit pension and other postretirement plans	(1.3)	(0.5)	(0.9)
Net unrealized (loss) gain on available-for-sale debt securities	(0.2)		0.1
Other Comprehensive Income (Loss), Before Tax	58.4	(12.6)	(48.5)
Income Tax Expense (Benefit) Related to Items of Other Comprehensive Income (Loss)	13.6	(2.7)	(10.8)
Other Comprehensive Income (Loss), Net of Tax	44.8	(9.9)	(37.7)
Comprehensive Income	316.5	78.7	146.9
Operating Revenues	2,235.5	1,855.4	1,952.4
Operating Expenses:
Natural gas	946.3	696.1	840.3
Operation and maintenance	465.8	458.6	474.1
Depreciation and amortization	213.1	197.3	181.7
Taxes, other than income taxes	160.1	148.4	154.0
Total Operating Expenses	1,785.3	1,649.0	1,650.1
Operating Income	450.2	206.4	302.3
Interest Expense, Net	106.6	105.5	104.4
Other (Expense) Income, Net	(3.4)	0.1	21.2
Income Before Income Taxes	340.2	101.0	219.1
Income Tax Expense	68.5	12.4	34.5
Spire Missouri
Net Income	144.1	130.2	115.0
Cash flow hedging derivative instruments:
Other Comprehensive Income (Loss), Net of Tax	(1.3)	(0.5)	(0.8)
Comprehensive Income	142.8	129.7	114.2
Operating Revenues	1,516.6	1,193.6	1,291.8
Operating Expenses:
Natural gas	786.8	515.8	629.8
Operation and maintenance	261.1	251.0	268.1
Depreciation and amortization	129.2	118.0	111.5
Taxes, other than income taxes	110.9	103.2	107.6
Total Operating Expenses	1,288.0	988.0	1,117.0
Operating Income	228.6	205.6	174.8
Interest Expense, Net	50.3	49.4	49.2
Other (Expense) Income, Net	(8.9)	(8.7)	2.7
Income Before Income Taxes	169.4	147.5	128.3
Income Tax Expense	$ 25.3	$ 17.3	$ 13.3