Commitments and Contingencies (Additional Information) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) claims claim	Dec. 31, 2018 USD ($) claims	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Number of claims dismissed	373	192
Number of claims settled | claims	31	25
Claims settlements amount	$ 5.0	$ 7.1
Legal fees	0.7	1.2
Environmental remediation expense (income)	$ 1.7	$ 0.7	$ 3.4
Projection period (years)	10 years	40 years
Connecticut Voluntary Corrective Action Program
Loss Contingencies [Line Items]
Environmental remediation expense	$ 1.4
Estimated total cleanup costs, accrual	$ 1.5