Postretirement Benefit Plans - Fair Value Changes Within Asset Categories for which Fair Value Measurements Use Significant Unobservable Inputs Level 3 (Detail) - Insurance Contracts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 1,243	$ 1,698
Sale proceeds (benefit payments)	(121)	(129)
Change in unrealized gain	37	(247)
Foreign exchange impact	46	(79)
Ending balance	$ 1,205	$ 1,243