Consolidated Statements of Total Equity (Unaudited) Statement - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]
Beginning balances (shares) at Sep. 30, 2019		47,997,366
Stock issued under employee incentive plans (shares)		27,993
Ending balances (shares) at Dec. 31, 2019		48,025,359
Beginning balances at Sep. 30, 2019	$ 808.9	$ 48.0	$ 602.2	$ 158.1	$ 0.6
Net income	16.8	0.0	0.0	16.9	(0.1)
Stock issued under employee incentive plans	0.0	0.0	0.0	0.0	0.0
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(0.2)	0.0	(0.2)	0.0	0.0
Stock-based compensation expense	0.5	0.0	0.5	0.0	0.0
Distributions to noncontrolling interests	(0.4)	0.0	0.0	0.0	(0.4)
Ending balances at Dec. 31, 2019	825.6	$ 48.0	602.5	175.0	0.1
Beginning balances (shares) at Sep. 30, 2020		48,061,921
Stock issued under employee incentive plans (shares)		14,722
Ending balances (shares) at Dec. 31, 2020		48,076,643
Beginning balances at Sep. 30, 2020	871.8	$ 48.1	603.9	218.9	0.9
Net income	22.1	0.0	0.0	22.0	0.1
Stock issued under employee incentive plans	0.0	0.0	0.0	0.0	0.0
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	(0.1)	0.0	(0.1)	0.0	0.0
Stock-based compensation expense	0.3	0.0	0.3	0.0	0.0
Ending balances at Dec. 31, 2020	$ 894.1	$ 48.1	$ 604.1	$ 240.9	$ 1.0