CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Income Statement [Abstract]
Revenues	$ 351.0	$ 333.8	$ 601.3	$ 639.7
Cost of sales	271.8	250.7	467.2	483.7
Selling, general and administrative expense	38.4	29.2	74.3	57.2
Equity in earnings of unconsolidated ventures	0.0	0.0	(0.6)	0.0
Interest and other income	(1.0)	(5.0)	(3.3)	(11.3)
Loss on extinguishment of debt	1.1	0.0	1.1	0.0
Income before income taxes	40.7	58.9	62.6	110.1
Income tax expense	9.1	13.9	14.5	26.9
Net income	$ 31.6	$ 45.0	$ 48.1	$ 83.2
Basic net income per common share	$ 0.62	$ 0.90	$ 0.95	$ 1.66
Weighted average number of common shares	50,795,094	50,147,639	50,807,945	50,106,735
Diluted net income per common share	$ 0.62	$ 0.89	$ 0.94	$ 1.65
Adjusted weighted average number of common shares	51,046,724	50,626,957	51,066,321	50,544,519