Schedule of Reconciliation of Defined Benefit Pension Plan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Fair value of plan assets at beginning of year	$ 120,287	$ 104,591
Actual return (loss) on plan assets	18,169	22,331
Benefits paid	(6,260)	(6,168)
Administrative expenses	(511)	(467)
Fair value of plan assets at end of year	131,685	120,287	$ 104,591
Benefit obligation at beginning of year	117,556	108,428
Service cost	615	725	689
Interest cost	3,357	4,237	4,063
Benefits paid	(6,260)	(6,168)
Actuarial (gain) loss	7,969	10,334
Benefit obligation at end of year	123,237	117,556	$ 108,428
Other non-current assets	8,449	2,731
Total amounts recognized at end of year	$ 8,449	$ 2,731