Pension Plans - Projected Benefit Obligation and Fair Value of Plan Assets (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Defined Benefit Plan Funded Status Of Plan [Abstract] | |||
| Projected benefit obligation at beginning of the year | $ 34,763 | $ 36,193 | |
| Service cost | 203 | 189 | $ 118 |
| Interest cost | 1,465 | 1,436 | 1,362 |
| Actuarial (gain) loss | (516) | (2,105) | |
| Benefits paid | (1,057) | (950) | |
| Projected benefit obligation at end of year | 34,858 | 34,763 | 36,193 |
| Fair value of plan assets at beginning of the year | 23,136 | 23,690 | |
| Actual return on plan assets | 1,365 | 396 | |
| Employer contributions | 991 | 0 | |
| Fair value of plan assets at end of the year | 24,435 | 23,136 | $ 23,690 |
| Unfunded pension obligation | $ 10,423 | $ 11,627 | |