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]
Common Stock, Shares, Outstanding		48,061,921
Beginning balances at Sep. 30, 2020	$ 871.8	$ 48.1	$ 603.9	$ 218.9	$ 0.9
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	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
Cash paid for shares withheld for taxes	(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
Common Stock, Shares, Outstanding		48,076,643
Common Stock, Shares, Outstanding		49,580,389
Beginning balances at Sep. 30, 2021	1,015.9	$ 49.6	636.2	329.1	1.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	40.5	0.0	0.0	40.5	0.0
Stock Issued During Period, Value, New Issues	1.7	0.1	1.6	0.0	0.0
Stock issued under employee incentive plans	0.0	0.0	0.0	0.0	0.0
Cash paid for shares withheld for taxes	(0.1)	0.0	0.1	0.0	0.0
Stock-based compensation expense	0.4	0.0	0.4	0.0	0.0
Ending balances at Dec. 31, 2021	$ 1,058.4	$ 49.7	$ 638.1	$ 369.6	$ 1.0
Common Stock, Shares, Outstanding		49,675,768