| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | Period [Axis] |
|---|
2016-01-01 - 2016-12-31 |
|---|
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |
Stock Option Activity |
Stock option activity during 2015 and 2016 was as follows
(aggregate intrinsic value in thousands):
|
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|
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|
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|
|
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| |
|
Number of
Options |
|
|
Weighted
Average
Exercise Price |
|
|
Weighted
Average
Remaining
Contractual
Term (in years) |
|
|
Aggregate
Intrinsic
Value |
|
|
Options outstanding at January 1, 2015
|
|
|
737,422 |
|
|
$ |
32.19 |
|
|
|
8.09 |
|
|
$ |
14,512 |
|
|
Options granted
|
|
|
204,700 |
|
|
|
63.07 |
|
|
|
9.21 |
|
|
|
1,724 |
|
|
Options exercised
|
|
|
(214,079 |
) |
|
|
42.75 |
|
|
|
N/A |
|
|
|
9,890 |
|
|
Options cancelled
|
|
|
(33,300 |
) |
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|
46.53 |
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|
N/A |
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|
N/A |
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|
Options outstanding at December 31, 2015
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|
694,743 |
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|
|
42.87 |
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|
|
7.70 |
|
|
|
20,717 |
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|
Options granted
|
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|
503,850 |
|
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|
57.98 |
|
|
|
9.28 |
|
|
|
297 |
|
|
Options exercised
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|
(57,397 |
) |
|
|
31.92 |
|
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|
N/A |
|
|
|
1,530 |
|
|
Options cancelled
|
|
|
(140,250 |
) |
|
|
57.13 |
|
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|
N/A |
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|
N/A |
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|
Options outstanding at December 31, 2016
|
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|
1,000,946 |
|
|
$ |
49.42 |
|
|
|
7.80 |
|
|
$ |
8,166 |
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Options exercisable at December 31, 2015
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|
106,330 |
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|
$ |
36.41 |
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|
5.83 |
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|
$ |
4,968 |
|
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|
Restricted Stock Activity |
Restricted stock activity during 2015 and 2016 was as follows:
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| |
|
Number of
Shares |
|
|
Weighted
Average
Grant-Date
Fair Value |
|
|
Unvested at January 1, 2015
|
|
|
722,028 |
|
|
$ |
39.77 |
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|
Granted
|
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|
503,052 |
|
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|
62.67 |
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|
Cancelled
|
|
|
(44,900 |
) |
|
|
49.55 |
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|
Vested
|
|
|
(235,618 |
) |
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|
34.93 |
|
|
|
|
|
|
|
|
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Unvested at December 31, 2015
|
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|
944,562 |
|
|
$ |
52.74 |
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|
Granted
|
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|
387,347 |
|
|
|
55.38 |
|
|
Cancelled
|
|
|
(122,178 |
) |
|
|
57.02 |
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|
Vested
|
|
|
(365,312 |
) |
|
|
47.18 |
|
|
|
|
|
|
|
|
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|
Unvested at December 31, 2016
|
|
|
844,419 |
|
|
$ |
55.76 |
|
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|
|
|
|
|
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|
Restricted Stock Unit Activity |
Restricted stock unit activity during 2015 and 2016 was as
follows:
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| |
|
Number of
Units |
|
|
Weighted
Average
Grant-Date
Fair Value |
|
|
Unvested at January 1, 2015
|
|
|
125,113 |
|
|
$ |
38.73 |
|
|
Granted
|
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|
217,994 |
|
|
|
61.77 |
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|
Cancelled
|
|
|
— |
|
|
|
— |
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|
Vested
|
|
|
(125,023 |
) |
|
|
32.38 |
|
|
|
|
|
|
|
|
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|
Unvested at December 31, 2015
|
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|
218,084 |
|
|
$ |
56.97 |
|
|
Granted
|
|
|
230,750 |
|
|
|
56.95 |
|
|
Cancelled
|
|
|
— |
|
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|
— |
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|
Vested
|
|
|
(175,235 |
) |
|
|
52.71 |
|
|
|
|
|
|
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|
Unvested at December 31, 2016
|
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|
273,599 |
|
|
$ |
59.68 |
|
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|
Schedule of Stock Options Valuation Assumptions |
The following table summarizes the grant-date fair value of options
and the assumptions used to develop the fair value estimates for
options granted during the years ended December 31, 2016 and
2015:
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| |
|
December 31, 2016 |
|
|
December 31, 2015 |
|
|
Weighted average grant-date fair value of options
|
|
$ |
18.96 |
|
|
$ |
21.78 |
|
|
Risk-free interest rate
|
|
|
1.4 |
% |
|
|
1.5 |
% |
|
Expected volatility
|
|
|
33 |
% |
|
|
35 |
% |
|
Expected life (in years)
|
|
|
5.5 |
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|
|
5.5 |
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|