Income Taxes (Tables)

12 Months Ended

Sep. 30, 2024

Income Tax Disclosure [Abstract]

Schedule of components of income tax expense (benefit)

	Year Ended September 30,
	2024		2023		2022
Current:
Federal	$	73.1	$	49.1	$	28.0
State	17.8		10.9		5.2
Foreign	0.7		0.9		0.4
	91.6		60.9		33.6
Deferred:
Federal	(7.1)		(4.9)		(3.4)
State	(1.6)		(1.1)		(0.6)
Foreign	—		—		—
	(8.7)		(6.0)		(4.0)
Income tax expense	$	82.9	$	54.9	$	29.6

Schedule of effective income tax rate reconciliation

	Year Ended September 30,
	2024		2023		2022
Computed tax at federal statutory rate (21%)	$	69.2	$	46.3	$	30.6
Income tax expense attributable to NCI	—		—		(7.6)
State income taxes, net of effect on federal tax	13.5		8.4		4.7
Transaction costs	—		—		2.0
Other, net (none in excess of 5% of computed tax)	0.2		0.2		(0.1)
Income tax expense	$	82.9	$	54.9	$	29.6

Schedule of deferred tax assets and liabilities

	September 30, 2024						September 30, 2023
	Assets		Liabilities		Net		Assets		Liabilities		Net
Accrued liabilities	$	6.7	$	—	$	6.7	6.0		—		6.0
Accrued vacation, incentive and severance	5.0		—		5.0		3.1		—		3.1
Capitalized research and development	4.7		—		4.7		2.3		—		2.3
Inventory	4.2		—		4.2		4.4		—		4.4
Stock-based compensation awards	3.0		—		3.0		2.2		—		2.2
Lease liabilities	1.0		—		1.0		1.4		—		1.4
Intangible assets	—		(10.9)		(10.9)		—		(13.9)		(13.9)
ROU assets	—		(1.0)		(1.0)		—		(1.4)		(1.4)
Property	—		(0.2)		(0.2)		—		(0.3)		(0.3)
Total deferred income taxes	$	24.6	$	(12.1)	$	12.5	$	19.4	$	(15.6)	$	3.8