Other Assets - Schedule of Company's Other Assets (Detail) - USD ($) $ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] | ||
| Deposits on future purchases of aircraft | $ 4,818 | $ 3,568 |
| Investment in Variable Interest Entity | 1,351 | |
| Investments (Officers' Deferred Compensation Plan) | 2,394 | 2,294 |
| Other | 1,196 | 316 |
| Total | $ 9,759 | $ 6,178 |