Schedule of Net Periodic Benefit Costs (Detail) - Pension Benefits - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Period Benefit Cost Assumptions [Line Items]
Service cost	$ (44)	$ 41	$ 12	$ 71
Interest cost	914	882	1,847	1,784
Expected return on plan assets	(513)	(482)	(1,076)	(964)
Administrative expenses	(3)	2	7	3
Settlement loss recognized	21	335	92	335
Net periodic pension cost	$ 375	$ 778	$ 882	$ 1,229