Pension and Employee Benefit Plans - Components of Pension and Employee Benefit Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation And Retirement Disclosure [Abstract]
Service cost	$ 447	$ 233	$ 204
Interest cost	1,426	1,412	1,428
Expected return on plan assets	(1,829)	(2,009)	(1,950)
Net amortization and deferral	212	258	177
Net periodic benefit income (cost)	$ 256	$ (106)	$ (141)