Stock Compensation Plans (Tables)
 12 Months Ended
Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Schedule of Share-based Compensation, Stock Options, Activity
A summary of activity related to stock option awards is as follows:
 
Shares Subject
to Options
(in thousands)
 
Weighted-Average Exercise Price per Share
 
Weighted-Average
Remaining
Contractual Term
(in years)
 
Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2012
12,488

 
$
6.17

 
 
 
 
Granted
3,151

 
$
3.54

 
 
 
 
Exercised
(111
)
 
$
2.90

 
 
 
 
Forfeitures and cancellations
(2,485
)
 
$
5.68

 
 
 
 
Outstanding at December 31, 2013
13,043

 
$
5.66

 
 
 
 
Granted
4,716

 
$
3.45

 
 
 
 
Exercised
(483
)
 
$
2.71

 
 
 
 
Forfeitures and cancellations
(6,160
)
 
$
5.77

 
 
 
 
Outstanding at December 31, 2014
11,116

 
$
4.96

 
6.6
 
$
3,161

Options exercisable at December 31, 2014
7,619

 
$
5.62

 
5.8
 
$
1,277

Options vested or expected to vest at December 31, 2014
10,412

 
$
5.08

 
6.5
 
$
2,698
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity
The following table summarizes activity related to restricted stock awards and restricted stock units:
 
Number of Shares (in thousands)
 
Weighted-Average
Grant Date
Fair Value
Outstanding at December 31, 2012
905

 
$
4.34

Grants and awards
1,822

 
$
3.32

Vested and released
(370
)
 
$
4.13

Forfeitures and cancellations
(224
)
 
$
3.87

Outstanding at December 31, 2013
2,133

 
$
3.47

Grants and awards
1,373

 
$
2.55

Vested and released
(724
)
 
$
3.13

Forfeitures and cancellations
(1,108
)
 
$
3.31

Outstanding at December 31, 2014
1,674

 
$
2.99
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions
The grant date value is based on the following assumptions:
Market condition option grants
 
Risk-free interest rate
2.6
%
Volatility
89.0
%
Dividend yield
—
%
Expected life (years)
8.0

Weighted-average grant date fair value
$
2.43

Share-based Compensation Expense
Following are the weighted-average underlying assumptions used to determine the fair value of stock option award grants and for stock purchase rights under the ESPP:
 
Years ended December 31,
Stock option grants
2014
 
2013
 
2012
Risk-free interest rate
1.16
%
 
0.96
%
 
1.64
%
Volatility
54.3
%
 
73.0
%
 
94.5
%
Dividend yield
—
%
 
—
%
 
—
%
Expected life (years)
4.1

 
5.3

 
7.4

Weighted-average grant date fair value
$
1.67

 
$
2.58

 
$
3.61

 
Years ended December 31,
ESPP stock purchase rights
2014
 
2013
 
2012
Risk-free interest rate
0.79
%
 
0.09
%
 
0.14
%
Volatility
67.2
%
 
68.9
%
 
68.2
%
Dividend yield
—
%
 
—
%
 
—
%
Expected life (years)
0.5

 
0.5

 
0.5

Weighted-average grant date fair value
$
0.91

 
$
1.17

 
$
1.13
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Total share-based compensation expense for all stock awards recognized in the consolidated statements of operations and comprehensive income (loss) is as follows (in thousands):
 
Years ended December 31,
 
2014
 
2013
 
2012
Total
$
11,519

 
$
9,527

 
$
10,790