Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands |
3 Months Ended | ||
|---|---|---|---|
Jan. 01, 2018 |
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Summary Of Significant Accounting Policies [Line Items] | |||
| Service cost component of defined benefit plan | $ 699 | $ 636 | |
| Accounting Standards Update 2016-01 [Member] | |||
| Summary Of Significant Accounting Policies [Line Items] | |||
| Adjustment to retained earnings | $ 1,100 | ||