STOCK-BASED COMPENSATION - Summary of Activity under Company's Stock Option Plans (Details) - $ / shares
shares in Thousands |
|
|
3 Months Ended |
Jan. 31, 2017 |
Jan. 31, 2016 |
Apr. 30, 2017 |
Apr. 30, 2016 |
| STOCK-BASED COMPENSATION |
|
|
|
|
| Shares, Outstanding, Beginning balance |
|
|
707
|
1,064
|
| Shares, Granted |
|
|
105
|
75
|
| Shares, Exercised |
|
|
(27)
|
(22)
|
| Shares, Outstanding, Ending balance |
707
|
1,064
|
785
|
1,117
|
| Shares, Exercisable |
|
|
485
|
842
|
| Weighted Average Exercise Price, Outstanding, Beginning balance |
|
|
$ 39.04
|
$ 26.38
|
| Weighted Average Exercise Price, Granted |
|
|
64.25
|
33.85
|
| Weighted Average Exercise Price, Exercised |
|
|
31.53
|
18.80
|
| Weighted Average Exercise Price, Outstanding, Ending balance |
$ 39.04
|
$ 26.38
|
42.68
|
27.03
|
| Weighted Average Exercise Price, Exercisable |
|
|
$ 28.17
|
$ 24.36
|
| Weighted Average Remaining Term, Outstanding |
7 years 9 months 26 days
|
6 years 4 months 10 days
|
7 years 11 months 9 days
|
6 years 11 months 1 day
|
| Weighted Average Remaining Term, Exercisable |
|
|
6 years 9 months 29 days
|
6 years 5 months 5 days
|
| Weighted Average Fair Value, Outstanding |
$ 10.22
|
$ 6.91
|
$ 11.29
|
$ 7.08
|
| Weighted Average Fair Value, Exercisable |
|
|
$ 7.51
|
$ 6.41
|