Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Net sales	$ 1,247.1	$ 988.3	$ 854.4
Cost of goods sold	860.9	650.3	542.6
Gross profit	386.2	338.0	311.8
Selling, general and administrative expenses	167.1	151.8	127.1
Amortization of intangible assets	51.2	22.2	22.2
Other operating income, net	(0.1)	0.0	0.0
Operating profit	168.0	164.0	162.5
Interest expense, net	43.2	54.7	0.0
Loss on refinancing of debt	1.6	0.0	0.0
Earnings before income taxes	123.2	109.3	162.5
Income tax expense	8.8	9.2	39.4
Net earnings including redeemable noncontrolling interest	114.4	100.1	123.1
Net earnings attributable to redeemable noncontrolling interest	86.8	76.6	123.1
Net earnings available to Class A common stockholders	$ 27.6	$ 23.5	$ 0.0
Earnings per Class A common share, basic (in usd per share)	$ 0.70	$ 0.60	$ 0
Earnings per Class A common share, diluted (in usd per share)	$ 0.70	$ 0.60	$ 0
Weighted-Average Class A common shares outstanding, basic (in shares)	39.5	39.4	0.0
Weighted-Average Class A common shares outstanding, diluted (in shares)	39.7	39.5	0.0