CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share, Diluted [Abstract]
Revenues	$ 333.8	$ 301.5	$ 639.7	$ 518.2
Cost of sales	250.7	245.6	483.7	414.8
Selling, General and Administrative Expense	29.2	22.0	57.2	44.9
Gain on sale of assets	0.0	0.0	0.0	(1.6)
Interest and other income	(5.0)	(2.0)	(11.3)	(3.7)
Income before income taxes	58.9	35.9	110.1	63.8
Income tax expense	13.9	9.0	26.9	16.1
Net income	$ 45.0	$ 26.9	$ 83.2	$ 47.7
Basic net income per common share	$ 0.90	$ 0.54	$ 1.66	$ 0.95
Weighted average number of common shares	50,147,639	49,943,373	50,106,735	49,916,927
Diluted net income per common share	$ 0.89	$ 0.54	$ 1.65	$ 0.95
Adjusted weighted average number of common shares	50,626,957	50,010,539	50,544,519	49,954,781