Stock Option and Purchase Plans (Tables)
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12 Months Ended |
Dec. 31, 2017 |
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| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
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| Summary of Weighted Average Fair Value of Options Granted |
Stock compensation expense recognized during the period is based on the value of the portion of share-based payment awards that is ultimately expected to vest during the period. Vesting requirements vary for directors, officers and key employees. In general, options granted to outside directors vest six months from the date of grant and options granted to officers and key employees straight line vest over a five-year period from the date of grant.
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2017 |
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2016 |
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2015 |
Weighted Average Fair Value of the Options Granted |
$ |
17.60 |
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$ |
16.85 |
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$ |
18.00 |
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| Summary of Weighted-Average Assumptions |
The weighted average fair value for these options was estimated at the date of grant using a Black-Scholes option pricing model with the following weighted-average assumptions:
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2017 |
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2016 |
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2015 |
Risk-free Interest Rate |
2.05% – 2.36% |
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1.08% – 2.34% |
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1.36% – 2.10% |
Dividend Yield |
—% |
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—% |
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—% |
Volatility Factor |
0.40 – 0.41 |
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0.40 – 0.45 |
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0.40 – 0.51 |
Expected Life in Years |
5.0 – 8.0 |
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4.0 – 8.0 |
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4.0 – 8.0 |
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| Compensation Expense Information Based on Fair Value of Stock Options |
The following table provides compensation expense information based on the fair value of stock options for the years ended December 31, 2017, 2016 and 2015:
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(In thousands) |
2017 |
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2016 |
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2015 |
Stock Compensation Expense |
$ |
2,598 |
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$ |
2,281 |
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$ |
2,274 |
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Tax Benefit |
(140 |
) |
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(145 |
) |
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(177 |
) |
Stock Compensation Expense, Net of Tax |
$ |
2,458 |
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$ |
2,136 |
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$ |
2,097 |
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| Summary of Company's Stock Option Activity and Related Information |
A summary of the Company’s stock option activity and related information for the years ended December 31 is as follows:
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2017 |
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2016 |
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2015 |
(Aggregate intrinsic value in
thousands) |
Options |
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Weighted
Average
Exercise
Price
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Aggregate
Intrinsic
Value
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Options |
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Weighted
Average
Exercise
Price |
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Aggregate
Intrinsic
Value |
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Options |
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Weighted
Average
Exercise
Price |
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Aggregate
Intrinsic
Value |
Outstanding at January 1 |
1,338,273 |
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$ |
14.85 |
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$ |
35,630 |
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1,444,954 |
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$ |
12.61 |
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$ |
30,675 |
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1,686,178 |
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$ |
9.43 |
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$ |
43,778 |
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Options Granted |
103,140 |
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$ |
38.41 |
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$ |
315 |
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104,900 |
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$ |
34.29 |
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$ |
(48 |
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105,742 |
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$ |
35.80 |
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$ |
(42 |
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Options Exercised |
(114,699 |
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$ |
11.24 |
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$ |
(3,467 |
) |
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(188,768 |
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$ |
7.20 |
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$ |
(5,029 |
) |
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(346,966 |
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$ |
4.25 |
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$ |
(10,808 |
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Options Forfeited |
(16,624 |
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$ |
27.91 |
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$ |
(225 |
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(22,813 |
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$ |
25.96 |
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$ |
(180 |
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— |
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$ |
— |
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$ |
— |
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Outstanding at December 31 |
1,310,090 |
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$ |
16.85 |
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$ |
32,253 |
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1,338,273 |
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$ |
14.85 |
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$ |
25,418 |
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1,444,954 |
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$ |
12.61 |
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$ |
32,928 |
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Exercisable at December 31 |
1,088,970 |
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$ |
12.84 |
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$ |
31,177 |
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1,091,561 |
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$ |
11.03 |
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$ |
24,898 |
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1,167,040 |
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$ |
9.20 |
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$ |
30,576 |
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| Summary of Weighted Average Exercise Prices and Contractual Lives for Outstanding and Exercisable Stock Options |
The following is a summary of weighted average exercise prices and contractual lives for outstanding and exercisable stock options as of December 31, 2017:
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Outstanding |
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Exercisable |
Exercise Price Range |
Shares |
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Weighted Average
Remaining Life
in Years
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Weighted
Average
Exercise Price
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Shares |
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Weighted Average
Remaining Life
in Years
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Weighted
Average
Exercise Price
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$ 3.07 - $ 3.67 |
470,757 |
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1.5 |
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$ |
3.29 |
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470,757 |
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1.5 |
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$ |
3.29 |
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$ 6.35 - $ 6.35 |
15,055 |
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0.2 |
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$ |
6.35 |
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15,055 |
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0.2 |
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$ |
6.35 |
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$ 8.83 - $15.68 |
374,619 |
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4.0 |
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$ |
11.52 |
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374,619 |
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4.0 |
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$ |
11.52 |
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$ 26.09 - $41.19 |
429,819 |
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8.0 |
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$ |
35.06 |
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208,699 |
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7.4 |
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$ |
33.41 |
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$ 52.77 - $52.77 |
19,840 |
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7.2 |
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$ |
52.77 |
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19,840 |
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7.2 |
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$ |
52.77 |
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1,310,090 |
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4.4 |
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$ |
16.85 |
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1,088,970 |
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3.6 |
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$ |
12.84 |
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| Fair Value for Options Granted under Employee Stock Purchase Plan |
The fair value for the options granted under the Employee Stock Purchase Plan was estimated at the date of grant using a Black-Scholes option pricing model with the following weighted-average assumptions:
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2017 |
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2016 |
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2015 |
Risk-free Interest Rate |
1.31 |
% |
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0.63 |
% |
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0.31 |
% |
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Dividend Yield |
— |
% |
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— |
% |
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— |
% |
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Volatility Factor |
0.26 |
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0.45 |
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0.40 |
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Expected Life in Years |
1.0 |
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1.0 |
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1.0 |
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