Summary of Stock Option Activity (Detail)
$ / shares in Units, $ in Thousands |
12 Months Ended |
|
Dec. 31, 2016
USD ($)
$ / shares
shares
|
|---|
| Number of options and SAR units |
|
|
| Number of shares outstanding, Beginning balance | shares |
2,406,455
|
|
| Number of shares, Options/SAR units granted | shares |
104,000
|
[1] |
| Number of shares, Options/SAR units exercised | shares |
(1,012,151)
|
|
| Number of shares, Options/SAR units forfeited or expired | shares |
(42,396)
|
|
| Number of shares outstanding, Ending balance | shares |
1,455,908
|
[2] |
| Number of shares outstanding, Vested or expected to vest at end of period | shares |
1,422,492
|
|
| Number of shares exercisable, Ending balance | shares |
972,229
|
[3] |
| Weighted-average exercise price |
|
|
| Weighted-average exercise price, Beginning balance | $ / shares |
$ 18.15
|
|
| Weighted average exercise price, Granted | $ / shares |
28.42
|
[1] |
| Weighted average exercise price, Exercised | $ / shares |
16.89
|
|
| Weighted average exercise price, Forfeited or expired | $ / shares |
17.93
|
|
| Weighted average exercise price, Ending balance | $ / shares |
19.76
|
[2] |
| Weighted average exercise price, Vested or expected to vest at end of period | $ / shares |
19.78
|
|
| Weighted average exercise price, exercisable | $ / shares |
$ 19.88
|
[3] |
| Weighted average remaining contractual term |
|
|
| Weighted average remaining contractual life, Outstanding at end of period |
4 years 8 months 12 days
|
[2] |
| Weighted average remaining contractual life, Vested or expected to vest at end of period |
4 years 8 months 12 days
|
|
| Weighted average remaining contractual life, Exercisable at end of period |
3 years 10 months 24 days
|
[3] |
| Aggregate intrinsic value |
|
|
| Aggregate intrinsic value, Outstanding | $ |
$ 20,077
|
[2] |
| Aggregate intrinsic value, Vested or expected to vest | $ |
19,587
|
|
| Aggregate intrinsic value, Exercisable | $ |
$ 13,286
|
[3] |
|
|