Other Finance Income (Costs) (Tables)

12 Months Ended

Dec. 31, 2019

Other Nonoperating Income (Expense) [Abstract]

Schedule of other finance income (costs)

	Year Ended December 31,			Three Months Ended December 31,			Year Ended September 30,
	2019			2018			2018
	(in millions)
Pension interest cost	$	(2.7	)	$	(0.7	)	$	(3.0	)
Expected return on pension plan assets		3.5			0.9			3.7
Foreign currency translation on senior bank debt		(0.8	)		(2.9	)		3.4
Foreign currency remeasurement on hedging instrument		3.2			2.0			—
	$	3.2		$	(0.7	)	$	4.1