Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||||
| Income tax expense | $ (1,622) | $ (2,799) | $ (9,324) | $ (5,515) |
| Accounting Standards Update 2016-09 [Member] | ||||
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||||
| Deferred tax liability | 1,000 | 1,000 | ||
| Income tax expense | 1,600 | |||
| Retained Earnings [Member] | Accounting Standards Update 2016-09 [Member] | ||||
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||||
| Cumulative effect adjustment | $ 1,000 | $ 1,000 | ||