Commitments and contingent liabilities (Detail) $ in Millions	3 Months Ended
	Mar. 29, 2020 USD ($)
Loss Contingencies [Line Items]
Estimated litigation liability	$ 0.3
Minimum
Loss Contingencies [Line Items]
Estimated time fram over which accrued amounts may be paid out	10 years
Maximum
Loss Contingencies [Line Items]
Estimated time fram over which accrued amounts may be paid out	15 years
Accrued Liabilities
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 0.7
Other Liability
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 6.0