Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 66	$ 65	$ 64
Interest cost	91	119	111
Expected return on plan assets	(10)	(17)	(8)
Amortization of prior service cost	65	76	18
Amortization of net transition obligation	0	(1)	(1)
Amortization of plan loss	0	28	22
Recognized actuarial net loss	17	14	7
Curtailments	0	160	0
Net periodic pension benefit cost	$ 229	$ 444	$ 213