CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Net income	$ 214.2	$ 161.6	$ 144.2
Net Income	214.2	161.6	153.9
Cash flow hedging derivative instruments:
Net hedging gain (loss) arising during the period	3.9	11.5	(4.0)
Reclassification adjustment for (income) loss included in net income	(1.5)	0.0	1.1
Net unrealized gain (loss) on cash flow hedging derivative instruments	2.4	11.5	(2.9)
Defined benefit pension and other postretirement benefit plans:
Amortization of actuarial loss (gain) included in net periodic pension and postretirement benefit cost	0.4	0.4	(0.3)
Net defined benefit pension and other postretirement benefit plans	0.4	0.4	(0.3)
Net unrealized gain (loss) on available-for-sale debt securities	0.3	(0.1)	0.0
Other Comprehensive Income (Loss), Before Tax	3.1	11.8	(3.2)
Income Tax Expense (Benefit) Related to Items of Other Comprehensive Income (Loss)	0.6	4.4	(1.0)
Other Comprehensive Income (Loss), Net of Tax	2.5	7.4	(2.2)
Comprehensive Income	216.7	169.0	142.0
Spire Missouri
Net income	129.3	113.0	105.9
Cash flow hedging derivative instruments:
Net hedging gain (loss) arising during the period	0.0	0.1	0.0
Reclassification adjustment for (income) loss included in net income	(0.1)	(0.2)	0.5
Net unrealized gain (loss) on cash flow hedging derivative instruments	(0.1)	(0.1)	0.5
Defined benefit pension and other postretirement benefit plans:
Net actuarial gain arising during the period	0.0	0.0	0.0
Amortization of actuarial loss (gain) included in net periodic pension and postretirement benefit cost	0.4	0.3	(0.3)
Net defined benefit pension and other postretirement benefit plans	0.4	0.3	(0.3)
Net unrealized gain (loss) on available-for-sale debt securities	0.2	(0.1)	(0.1)
Other Comprehensive Income (Loss), Before Tax	0.5	0.1	0.1
Income Tax Expense (Benefit) Related to Items of Other Comprehensive Income (Loss)	0.1	0.0	0.2
Other Comprehensive Income (Loss), Net of Tax	0.4	0.1	(0.1)
Comprehensive Income	$ 129.7	$ 113.1	$ 105.8