Compensation and Other Benefit Plans (Tables)
|
12 Months Ended |
Dec. 31, 2015 |
|---|
| Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] |
|
| Stock Option Activity |
The following table summarizes the Company’s stock option activity:
|
|
|
2015
|
|
|
2014
|
|
|
2013
|
|
|
|
|
Number of
shares
|
|
|
Weighted
Average
Exercise
Price
Per Share
|
|
|
Number of
shares
|
|
|
Weighted
Average
Exercise
Price
Per Share
|
|
|
Number of
shares
|
|
|
Weighted
Average
Exercise
Price
Per Share
|
|
|
Outstanding at beginning of year
|
|
|
7,702,309
|
|
|
$
|
8.15
|
|
|
|
7,216,041
|
|
|
$
|
8.42
|
|
|
|
6,788,383
|
|
|
$
|
8.99
|
|
|
Granted
|
|
|
1,797,222
|
|
|
|
3.78
|
|
|
|
1,891,989
|
|
|
|
6.69
|
|
|
|
1,168,203
|
|
|
|
3.13
|
|
|
Exercised
|
|
|
(163,663
|
)
|
|
|
1.89
|
|
|
|
(915,911
|
)
|
|
|
3.91
|
|
|
|
(589,355
|
)
|
|
|
2.26
|
|
|
Forfeited, expired or cancelled
|
|
|
(1,645,571
|
)
|
|
|
12.51
|
|
|
|
(489,810
|
)
|
|
|
14.36
|
|
|
|
(151,190
|
)
|
|
|
17.46
|
|
|
Outstanding at end of year
|
|
|
7,690,297
|
|
|
|
6.33
|
|
|
|
7,702,309
|
|
|
|
8.15
|
|
|
|
7,216,041
|
|
|
|
8.42
|
|
|
Exercisable at end of year
|
|
|
5,604,615
|
|
|
$
|
6.93
|
|
|
|
4,908,925
|
|
|
$
|
9.98
|
|
|
|
4,814,926
|
|
|
$
|
11.14
|
|
|
Weighted-average grant-date fair value
|
|
|
|
|
|
$
|
2.60
|
|
|
|
|
|
|
$
|
4.49
|
|
|
|
|
|
|
$
|
2.27
|
|
|
| Unvested RSU Activity |
Unvested RSU activity for the year ended December 31, 2015 is summarized below:
|
|
|
|
|
|
|
Weighted-
|
|
|
|
|
Number of
|
|
|
Average Grant-
|
|
|
|
|
Shares
|
|
|
Date Fair Value
|
|
|
Unvested balance at January 1, 2015
|
|
|
1,953,879
|
|
|
$
|
5.46
|
|
|
Granted
|
|
|
2,113,432
|
|
|
|
3.25
|
|
|
Vested
|
|
|
(1,184,147
|
)
|
|
|
4.64
|
|
|
Forfeited
|
|
|
(757,403
|
)
|
|
|
4.48
|
|
|
Unvested balance at December 31, 2015
|
|
|
2,125,761
|
|
|
$
|
4.07
|
|
|
| Weighted Average Assumptions |
The fair value of stock options granted during the years ended December 31, 2015, 2014, and 2013, was estimated based on the following weighted average assumptions for:
|
|
|
Year Ended December 31,
|
|
|
|
|
2015
|
|
|
2014
|
|
|
2013
|
|
|
Dividend yield
|
|
|
0
|
%
|
|
|
0
|
%
|
|
|
0
|
%
|
|
Expected volatility
|
|
|
84
|
%
|
|
|
92
|
%
|
|
|
92
|
%
|
|
Risk-free interest rate
|
|
|
1.40
|
%
|
|
|
1.72
|
%
|
|
|
0.89
|
%
|
|
Expected term
|
|
5.6 years
|
|
|
5.6 years
|
|
|
5.6 years
|
|
|
| Stock-based Compensation expense |
The following table shows total stock-based compensation expense for stock options, RSUs and ESPP in the consolidated statements of comprehensive loss (in thousands):
|
|
|
Year Ended December 31,
|
|
|
|
|
2015
|
|
|
2014
|
|
|
2013
|
|
|
Research and development
|
|
$
|
5,022
|
|
|
$
|
5,557
|
|
|
$
|
2,358
|
|
|
Selling, general and administrative
|
|
|
4,705
|
|
|
|
5,215
|
|
|
|
2,741
|
|
|
Total stock-based compensation expense
|
|
$
|
9,727
|
|
|
$
|
10,772
|
|
|
$
|
5,099
|
|
|