Business Acquisitions and Divestitures - Narrative (Details) $ / shares in Units, shares in Millions, $ in Millions				1 Months Ended	3 Months Ended			6 Months Ended
	Mar. 10, 2021 USD ($)	Mar. 30, 2020 USD ($)	Nov. 21, 2019 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)
Business Acquisition [Line Items]
Proceeds from divestiture of businesses				$ 13.1
Pre-tax loss					$ (34.1)		$ 3.0	$ (65.7)	$ 3.0
Proceeds from divestitures, net of cash divested		$ 165.7							222.4
Molding Technology Solutions
Business Acquisition [Line Items]
Business acquisition and integration costs					6.6		$ 3.9	12.3	$ 57.7
Percentage of voting interests acquired			100.00%
Share price (in dollars per share) | $ / shares			$ 11.80
Exchange ratio of common stock issued (in shares)			0.1612
Payments to acquire business, gross			$ 1,643.0
Business acquisition, common stock shares issued (in shares) | shares			11.4
Repayment of Milacron debt, including accrued interest			$ 772.9
Identifiable intangible assets					815.0			815.0
Cimcool
Business Acquisition [Line Items]
Proceeds from divestitures, net of cash divested		$ 222.4
Red Valve
Business Acquisition [Line Items]
Proceeds from divestiture of businesses						$ 59.4
Pre-tax loss								31.6
Trade receivables, net						$ 5.0
Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation								3.8
Discontinued Operation, Transaction Costs								2.9
ABEL
Business Acquisition [Line Items]
Pre-tax loss					(34.1)			(34.1)
Proceeds from divestitures, net of cash divested	$ 103.5
Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation					6.7			6.7
Discontinued Operation, Transaction Costs					$ 3.0			$ 3.8
Proceeds from Divestiture of Businesses, Including Working Capital Adjustments	$ 106.3