Restructuring - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Apr. 14, 2021	Mar. 31, 2021	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2020
Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge, employee severance						$ 0.4
Selling, General and Administrative Expense [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge, employee severance						0.3
Automotive Racing Market Segment [Member]
Restructuring Cost And Reserve [Line Items]
Non-cash restructuring charge			$ 3.4
Restructuring charge, write-down of after-market inventory to salvage value			1.3
Restructuring charge, employee severance			1.0			$ 0.7
Restructuring charges, contract terminations costs			0.5
Restructuring severance accrual		$ 0.4
Automotive Racing Market Segment [Member] | Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Non-cash restructuring charge			2.8
Automotive Racing Market Segment [Member] | Selling, General and Administrative Expense [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge, employee severance			$ 0.6
Fayetteville, Arkansas Manufacturing Facility [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charge, employee severance					$ 1.6
Restructuring severance accrual		0.3
Accelerated depreciation					7.6
Restructuring charge, write-down of inventory to net salvage value					3.2
Restructuring charge, accelerated amortization of right of use assets					0.6
Relocation costs		$ 0.8		$ 1.8				$ 2.9
Relocation costs recognition period							3 months
Other costs								0.4
Additional charges to cost of sales								$ 3.3
Fayetteville, Arkansas Manufacturing Facility [Member] | Subsequent Event [Member]
Restructuring Cost And Reserve [Line Items]
Purchase price	$ 7.6
Fayetteville, Arkansas Manufacturing Facility [Member] | Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Non-cash restructuring charge					$ 13.0