Employee Benefits (Detail) - Components of Net Periodic Pension Expense - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Service cost	$ 2,620	$ 2,630	$ 2,545
Interest cost	790	1,190	1,075
Expected return on plan assets	(345)	(540)	(340)
Recognition of actuarial loss	300	75	30
Recognition of termination benefits	85	30	455
Total defined benefit pension expense	$ 3,450	$ 3,385	$ 3,765