Employee Benefit Plans - Summary of Change in Projected Benefit Obligation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in projected benefit obligation:
Projected benefit obligation at the beginning of the year	$ 9,711	$ 7,909
Service cost	1,933	1,601	$ 1,638
Interest cost	645	599	550
Benefits paid	(1,001)	(837)
Actuarial (gain)/loss	(1,471)	677
Acquisition	0	47
Effect of exchange rate changes	488	(285)
Projected benefit obligation at the end of the year	10,305	9,711	$ 7,909
Unfunded amount–non-current	3,377	1,977
Unfunded amount–current	13	2,094
Total accrued liability	3,390	4,071
Accumulated benefit obligation	$ 7,022	$ 6,533