Commitments and Contingencies - Additional Information (Detail) $ in Millions		6 Months Ended
	Jan. 02, 2020 Area	Jun. 30, 2020 USD ($)
Loss Contingencies [Line Items]
Record of decision description		The ROD includes a combination of dredging, capping, and enhanced natural recovery that would take approximately thirteen years to construct plus additional time for monitored natural recovery
Estimated present value cost for construction and recovery | $		$ 1,050
Remediation plan description		the EPA indicated that it expected PRPs to submit a plan during 2019 to start remediation of the river and harbor per the original ROD within the next two to three years. The EPA also indicated that it expected allocation of amounts among the parties to be determined in the same two to three-year time frame.
Number of areas to perform remedial design work | Area	5
Percentage of acreage on remediation	52.00%
Minimum [Member]
Loss Contingencies [Line Items]
Remediation plan due date		2 years
Remediation plan allocation of amount due date		2 years
Maximum [Member]
Loss Contingencies [Line Items]
Remediation plan due date		3 years
Remediation plan allocation of amount due date		3 years