| Share-based Payment Arrangement, Option, Activity [Table Text Block] |
| |
|
Shares |
|
|
Weighted Average Exercise Price |
|
|
Weighted Average Remaining Contractual Term (years) |
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|
Aggregate Intrinsic Value |
|
| |
|
|
|
|
|
|
|
|
|
|
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|
(In Thousands) |
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| Six Months Ended June 30, 2019: |
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|
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|
|
|
|
|
|
|
|
|
|
|
|
|
| Outstanding at January 1, 2019 |
|
|
1,238,748 |
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|
$ |
13.02 |
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|
|
5.2 |
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|
$ |
23,355 |
|
| Granted |
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|
10,500 |
|
|
|
34.44 |
|
|
|
9.7 |
|
|
|
(2 |
) |
| Exercised |
|
|
(188,500 |
) |
|
|
5.58 |
|
|
|
1.8 |
|
|
|
5,014 |
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| Forfeited |
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|
(13,000 |
) |
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|
29.93 |
|
|
|
7.4 |
|
|
|
56 |
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| Outstanding at June 30, 2019 |
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|
1,047,748 |
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|
$ |
14.37 |
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|
|
5.3 |
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|
$ |
21,233 |
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
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| Exercisable at June 30, 2019 |
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|
328,800 |
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|
$ |
8.13 |
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|
3.7 |
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|
$ |
8,964 |
|
| |
|
|
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|
|
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| Six Months Ended June 30, 2018: |
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| Outstanding at January 1, 2018 |
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|
1,666,834 |
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|
$ |
10.68 |
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|
|
5.5 |
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|
$ |
51,377 |
|
| Granted |
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|
12,750 |
|
|
|
41.50 |
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|
|
9.7 |
|
|
|
(9 |
) |
| Exercised |
|
|
(175,836 |
) |
|
|
4.90 |
|
|
|
3.1 |
|
|
|
6,317 |
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| Forfeited |
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(6,000 |
) |
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|
19.50 |
|
|
|
7.7 |
|
|
|
128 |
|
| Outstanding at June 30, 2018 |
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|
1,497,748 |
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|
$ |
11.58 |
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|
5.3 |
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|
$ |
43,787 |
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
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| Exercisable at June 30, 2018 |
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|
748,600 |
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|
$ |
7.34 |
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|
3.9 |
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|
$ |
25,811 |
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| Nonvested Restricted Stock Shares Activity [Table Text Block] |
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|
Shares |
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|
Weighted Average Grant Date Fair Value |
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| Six Months Ended June 30, 2019: |
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|
|
|
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| Non-vested at January 1, 2019 |
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|
44,076 |
|
|
$ |
38.44 |
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| Granted |
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|
23,474 |
|
|
|
34.03 |
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| Vested |
|
|
(5,200 |
) |
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|
20.31 |
|
| Forfeited |
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|
(2,500 |
) |
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|
38.17 |
|
| Non-vested at June 30, 2019 |
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|
59,850 |
|
|
$ |
38.95 |
|
| |
|
|
|
|
|
|
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| Six Months Ended June 30, 2018: |
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| Non-vested at January 1, 2018 |
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|
120,676 |
|
|
$ |
10.29 |
|
| Granted |
|
|
11,850 |
|
|
|
41.29 |
|
| Vested |
|
|
(61,700 |
) |
|
|
5.81 |
|
| Forfeited |
|
|
- |
|
|
|
- |
|
| Non-vested at June 30, 2018 |
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|
70,826 |
|
|
$ |
19.38 |
|
|