Computation of Earnings Per Share - Additional Information (Detail) - shares |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Stock Options [Member] | |||
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | |||
| Stock options excluded from calculation of diluted earnings per share | 56,850 | 58,350 | 25,000 |