Employee Benefit Plans - Expected Benefit Payments (Detail) $ in Thousands |
Dec. 31, 2016
USD ($)
|
|---|---|
| Defined Benefit Pension Plans | |
| Defined Benefit Plan Disclosure [Line Items] | |
| 2017 | $ 3,615 |
| 2018 | 3,642 |
| 2019 | 3,629 |
| 2020 | 3,658 |
| 2021 | 3,724 |
| Next 5 years | 17,931 |
| OPEB | |
| Defined Benefit Plan Disclosure [Line Items] | |
| 2017 | 434 |
| 2018 | 389 |
| 2019 | 346 |
| 2020 | 304 |
| 2021 | 266 |
| Next 5 years | $ 860 |