CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Noncontrolling Interest
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Beginning Balance at Sep. 30, 2018	$ 674.5	$ 41.9	$ 506.3	$ 125.1	$ 1.2
Net income	36.3	0.0	0.0	33.0	3.3
Stock Issued During Period, Value, New Issues	100.7	6.0	94.7	0.0	0.0
Issuances of common stock, Value	0.0	0.1	0.1	0.0	0.0
Stock-based compensation expense	1.3	0.0	1.3	0.0	0.0
Distributions to noncontrolling interests	(3.9)	0.0	0.0	0.0	(3.9)
Ending Balances at Sep. 30, 2019	808.9	48.0	602.2	158.1	0.6
Net income	61.7	0.0	0.0	60.8	0.9
Issuances of common stock, Value	0.1	0.1	0.0	0.0	0.0
Stock-based compensation expense	2.0	0.0	2.0	0.0	0.0
Distributions to noncontrolling interests	(0.6)	0.0	0.0	0.0	(0.6)
Cash paid for shares withheld for taxes	(0.3)	0.0	(0.3)	0.0	0.0
Ending Balances at Sep. 30, 2020	871.8	48.1	603.9	218.9	0.9
Net income	110.5	0.0	0.0	110.2	0.3
Stock Issued During Period, Value, New Issues	33.4	1.4	32.0	0.0	0.0
Issuances of common stock, Value	0.1	0.1	0.0	0.0	0.0
Purchase of noncontrolling interest, net	(1.8)	0.0	(1.7)	0.0	(0.1)
Stock-based compensation expense	2.6	0.0	2.6	0.0	0.0
Distributions to noncontrolling interests	(0.1)	0.0	0.0	0.0	(0.1)
Cash paid for shares withheld for taxes	(0.6)	0.0	(0.6)	0.0	0.0
Ending Balances at Sep. 30, 2021	$ 1,015.9	$ 49.6	$ 636.2	$ 329.1	$ 1.0