XML 58 R30.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-based Compensation (Tables)
 12 Months Ended
Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Schedule of stock-based compensation expense
Stock-based compensation expense is included in the consolidated statements of operations as follows (in thousands):
 
 
Years Ended December 31,
 
2017
 
2016
 
2015
Research and development
$
1,444

 
$
1,033

 
$
935

Selling, general and administrative
5,647

 
4,640

 
4,191

Total
$
7,091

 
$
5,673

 
$
5,126
Assumptions used to estimate the fair value of option grants
For options granted to non-employees, the Black-Scholes option-pricing model was applied using the following assumptions during the year ended December 31, 2017:
 
 
Year Ended 
December 31,
 
 
2017
Remaining contractual option life (years)
 
9.78

Volatility
 
60.6
%
Risk-free interest rate
 
2.4
%
Expected dividend yield (1)
 
0.0
%
(1) We do not currently pay dividends, and thus the dividend rate variable in the Black-Scholes-Merton option-pricing model is zero.
The following summarize the ranges of weighted-average assumptions used to estimate the fair value of employee stock options granted:
 
Years Ended December 31,
 
2017
 
2016
 
2015
Expected life (years)
5.4

 
5.3

 
6.1

Volatility
62.2
%
 
64.2
%
 
66.1
%
Risk-free interest rate
2.0
%
 
1.3
%
 
1.7
%
Expected dividend yield (1)
0.0
%
 
0.0
%
 
0.0
%
Schedule of share-based compensation, stock options, activity
For options granted to non-employees, the Black-Scholes option-pricing model was applied using the following assumptions during the year ended December 31, 2017:
 
 
Year Ended 
December 31,
 
 
2017
Remaining contractual option life (years)
 
9.78

Volatility
 
60.6
%
Risk-free interest rate
 
2.4
%
Expected dividend yield (1)
 
0.0
%
(1) We do not currently pay dividends, and thus the dividend rate variable in the Black-Scholes-Merton option-pricing model is zero.
Schedule of share-based compensation, RSA activity
The following table summarizes RSA activity in 2017:
 
Number
of
Shares
 
Weighted Average
Grant Date
Fair Value
Per Share
 
(in thousands)
 
 
Non-vested balance at January 1, 2017
230

 
$
3.82

Granted
143

 
$
4.75

Vested
(214
)
 
$
3.81

Forfeited/Expired
—

 
$
—

Non-vested balance at December 31, 2017
159

 
$
4.68
Schedule of share-based compensation, RSU activity
The following table summarizes RSU activities in 2017:
 
Number
of
Shares
 
Weighted Average
Grant Date
Fair Value
Per Share
 
(in thousands)
 
 
Non-vested balance at January 1, 2017
617

 
$
3.69

Granted
275

 
$
4.22

Vested
(302
)
 
$
3.40

Forfeited/Expired
(30
)
 
$
4.12

Non-vested balance at December 31, 2017
560

 
$
4.08
Share-based compensation, performance shares sward outstanding activity
The following table summarizes PSU activities in 2017:
 
Number
of
Shares
 
Weighted Average
Grant Date
Fair Value
Per Share
 
(in thousands)
 
 
Non-vested balance at January 1, 2017
831

 
$
3.88

Granted
276

 
$
4.25

Vested
(651
)
 
$
3.84

Forfeited/Expired
(27
)
 
$
3.65

Non-vested balance at December 31, 2017
429

 
$
4.20

The following table summarizes PBO activities in 2017:
 
Number
of
Shares
 
Weighted Average
Grant Date
Fair Value
Per Share
 
(in thousands)
 
 
Non-vested balance at January 1, 2017
—

 
$
—

Granted
1,720

 
$
2.54

Vested
—

 
$
—

Forfeited/Expired
—

 
$
—

Non-vested balance at December 31, 2017
1,720

 
$
2.54