Commitments and Contingencies - Range of Environmental Liability and Number of Active Sites for Environmental Matters (Detail) - Environmental Related Matters [Member] $ in Millions	Dec. 31, 2019 USD ($) site	Dec. 31, 2018 USD ($) site
Environmental Matters Range Of Estimated Liability And Active Sites Numbers [Line Items]
Number of active environmental investigation and remediation sites | site	28	31
Maximum [Member]
Environmental Matters Range Of Estimated Liability And Active Sites Numbers [Line Items]
Possible High End Range of Environmental Liability | $	$ 108.4	$ 115.9