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Pension Benefit Plan - Summarization of Components of Net Periodic Pension Cost (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Compensation And Retirement Disclosure [Abstract]        
Service cost $ 306 $ 310 $ 603 $ 607
Interest cost 147 184 290 360
Expected return on plan assets (307) (271) (606) (530)
Amortization of actuarial losses 75 45 148 88
Net periodic pension cost $ 221 $ 268 $ 435 $ 525