Revenue - Summary of revenue by geography (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Consolidated net sales	$ 348.8	$ 573.0	$ 702.1	$ 1,158.4
United States
Disaggregation of Revenue [Line Items]
Consolidated net sales	208.2	370.9	432.9	755.8
Europe
Disaggregation of Revenue [Line Items]
Consolidated net sales	68.1	93.8	129.3	195.2
Asia Pacific
Disaggregation of Revenue [Line Items]
Consolidated net sales	48.9	67.8	86.8	121.1
Mexico
Disaggregation of Revenue [Line Items]
Consolidated net sales	10.7	15.6	23.9	37.5
Canada
Disaggregation of Revenue [Line Items]
Consolidated net sales	7.1	16.0	14.9	29.4
Other
Disaggregation of Revenue [Line Items]
Consolidated net sales	$ 5.8	$ 8.9	$ 14.3	$ 19.4