Schedule of Reconciliation of Defined Benefit Pension Plan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Pension Plans And Defined Benefit Postretirement Plans Disclosure [Abstract]
Fair value of plan assets at beginning of year	$ 118,667	$ 109,677
Actual return (loss) on plan assets	(7,522)	15,533
Benefits paid	(6,031)	(5,846)
Administrative expenses	(523)	(697)
Fair value of plan assets at end of year	104,591	118,667	$ 109,677
Benefit obligation at beginning of year	116,056	110,949
Service cost	689	721	926
Interest cost	4,063	4,465	4,997
Benefits paid	(6,031)	(5,846)
Actuarial (gain) loss	(6,350)	5,767
Benefit obligation at end of year	108,427	116,056	$ 110,949
Other non-current assets		2,611
Other non-current liabilities	3,836
Total amounts recognized at end of year	$ 3,836	$ 2,611