Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 204.2	$ 237.6	$ 705.7	$ 639.9
Cost of goods sold	135.5	147.1	457.5	404.8
Gross profit	68.7	90.5	248.2	235.1
Selling, general and administrative expenses	32.6	32.2	116.6	92.0
Amortization of intangible assets	5.5	5.5	16.6	16.6
Operating profit	30.6	52.8	115.0	126.5
Interest expense, net	15.3	0.0	41.2	0.0
Earnings before income taxes	15.3	52.8	73.8	126.5
Income tax expense	1.1	12.5	9.2	30.1
Net earnings including redeemable noncontrolling interest	14.2	40.3	64.6	96.4
Less: Net earnings attributable to redeemable noncontrolling interest	10.9	40.3	51.1	96.4
Net earnings available to Class A common stockholders	$ 3.3	$ 0.0	$ 13.5	$ 0.0
Earnings per Class A common share, basic (in usd per share)	$ 0.08	$ 0	$ 0.34	$ 0
Earnings per Class A common share, diluted (in usd per share)	$ 0.08	$ 0	$ 0.34	$ 0
Weighted-Average Class A common shares outstanding, basic (in shares)	39.4	0.0	39.4	0.0
Weighted-Average Class A common shares outstanding, diluted (in shares)	39.5	0.0	39.5	0.0