Earnings per Common Share - Additional Information (Detail) - shares |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Restricted Stock Units [Member] | ||
| Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | ||
| Anti-dilutive securities excluded from computation of earnings per share, amount | 342,004,000 | 118,773,000 |