Pensions and Other Post-retirement Benefits - Schedule of Reconciliation of Level Three Assets (Detail) - Significant Unobservable Inputs (Level 3) - Insurance contracts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at January 1	$ 17,033	$ 17,834
Net realized and unrealized losses	5,602	(957)
Net purchases, issuances and settlements	(1,133)	156
Fair value of plan assets at December 31	$ 21,502	$ 17,033