STOCK BASED COMPENSATION - stock option plan (Detail) - USD ($)
|
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Weighted average exercise price |
|
|
|
| Total unrecognized compensation (in years) |
2 years 6 months
|
|
|
| Stock option |
|
|
|
| Number of shares |
|
|
|
| Options outstanding, beginning of year (in shares) |
1,233,606
|
1,115,841
|
|
| Options granted (in shares) |
182,118
|
176,093
|
|
| Options exercised (in shares) |
(66,024)
|
(39,448)
|
|
| Options forfeited (in shares) |
(30,441)
|
(18,880)
|
|
| Options outstanding, end of year (in shares) |
1,319,259
|
1,233,606
|
1,115,841
|
| Options exercisable (in shares) |
729,483
|
667,808
|
|
| Options vested and expected to vest (in shares) |
1,245,713
|
1,158,706
|
|
| Weighted average exercise price |
|
|
|
| Options outstanding, beginning of year (in dollars per share) |
$ 17.52
|
$ 16.57
|
|
| Options granted (in dollars per share) |
26.15
|
22.81
|
|
| Options exercised (in dollars per share) |
16.01
|
14.15
|
|
| Options forfeited (in dollars per share) |
20.15
|
18.00
|
|
| Options outstanding, end of year (in dollars per share) |
18.73
|
17.52
|
$ 16.57
|
| Options exercisable (in dollars per share) |
16.37
|
15.68
|
|
| Options vested and expected to vest (in dollars per share) |
$ 18.56
|
$ 17.37
|
|
| Options outstanding, end of year (in years) |
6 years 3 months 18 days
|
6 years 9 months 18 days
|
|
| Options exercisable (in years) |
4 years 7 months 6 days
|
5 years
|
|
| Options vested and expected to vest (in years) |
6 years 2 months 12 days
|
6 years 7 months 6 days
|
|
| Aggregate intrinsic value of options outstanding |
$ 23,000,000
|
|
|
| Aggregate intrinsic value of options exercisable |
14,500,000
|
|
|
| Total unrecognized compensation |
$ 1,200,000
|
|
|
| Weighted average fair value of options granted |
$ 2.94
|
$ 2.55
|
$ 2.75
|
| Total intrinsic value from options exercised |
$ 971,000
|
$ 299,000
|
$ 32,000
|
| Cash received from options exercised |
$ 890,000
|
$ 558,000
|
$ 74,000
|