Income Taxes - Component of Income Taxes Expenses (Detail) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Components of income tax expense (benefit): | |||
| Currently payable (receivable) | $ 1,500 | $ 100 | $ 800 |
| Deferred income tax expense (benefit) | (4,300) | (28,700) | 4,200 |
| Income tax expense (benefit) | $ (2,777) | $ (28,611) | $ 5,003 |