Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net sales	$ 257.5	$ 216.5	$ 501.5	$ 402.3
Cost of goods sold	169.3	137.5	322.0	257.7
Gross profit	88.2	79.0	179.5	144.6
Selling, general and administrative expenses	47.5	32.6	84.0	59.8
Amortization of intangible assets	5.6	5.6	11.1	11.1
Operating profit	35.1	40.8	84.4	73.7
Interest expense, net	14.3	0.0	25.9	0.0
Earnings before income taxes	20.8	40.8	58.5	73.7
Income tax expense	2.2	9.8	8.1	17.6
Net earnings including redeemable noncontrolling interest	18.6	31.0	50.4	56.1
Less: Net earnings attributable to redeemable noncontrolling interest	14.4	31.0	40.2	56.1
Net earnings available to Class A common stockholders	$ 4.2	$ 0.0	$ 10.2	$ 0.0
Earnings per Class A common share, basic (in usd per share)	$ 0.11	$ 0	$ 0.26	$ 0
Earnings per Class A common share, diluted (in usd per share)	$ 0.11	$ 0	$ 0.26	$ 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	39.4	0.0