|
Note 11 - Stock-based Compensation (Tables)
|
12 Months Ended |
|
Dec. 31, 2014
|
| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] |
|
| Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] |
|
|
|
Year Ended December 31,
|
|
|
|
|
2014
|
|
|
2013
|
|
|
2012
|
|
|
Risk-free interest rate
|
|
|
—
|
|
|
|
1.41
|
%
|
|
|
1.32
|
%
|
|
Expected life (in years)
|
|
|
—
|
|
|
|
6.25
|
|
|
|
6.22
|
|
|
Dividend yield
|
|
|
—
|
|
|
|
—
|
|
|
|
—
|
|
|
Expected volatility
|
|
|
—
|
|
|
|
50
|
%
|
|
|
50
|
%
|
|
| Schedule of Share-based Compensation, Activity [Table Text Block] |
|
|
|
Number of
Shares
|
|
|
Weighted
Average
Exercise
Price Per Share
|
|
|
Weighted
Average
Remaining
Contractual
Life
|
|
|
Aggregate
Intrinsic
Value
|
|
|
Outstanding at December 31, 2013
|
|
|
3,883,097
|
|
|
$
|
9.26
|
|
|
|
6.33
|
|
|
$
|
16,229
|
|
|
Granted
|
|
|
—
|
|
|
|
—
|
|
|
|
|
|
|
|
|
|
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Exercised
|
|
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(788,196
|
)
|
|
|
5.45
|
|
|
|
|
|
|
|
|
|
|
Canceled
|
|
|
(89,307
|
)
|
|
|
12.52
|
|
|
|
|
|
|
|
|
|
|
Outstanding at December 31, 2014
|
|
|
3,005,594
|
|
|
$
|
10.16
|
|
|
|
6.12
|
|
|
$
|
25,302
|
|
|
Exercisable at December 31, 2014
|
|
|
2,349,476
|
|
|
$
|
9.69
|
|
|
|
5.82
|
|
|
$
|
20,880
|
|
|
Vested and expected to vest in the future as of December 31, 2014
|
|
|
3,001,391
|
|
|
$
|
10.16
|
|
|
|
6.12
|
|
|
$
|
25,273
|
|
|
| Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] |
|
|
|
Number of
Shares
|
|
|
Weighted
Average
Grant Date Fair Value Per Share
|
|
|
Outstanding at December 31, 2013
|
|
|
3,209,567
|
|
|
$
|
11.69
|
|
|
Granted
|
|
|
2,878,836
|
|
|
|
13.99
|
|
|
Vested
|
|
|
(1,098,924
|
)
|
|
|
12.61
|
|
|
Canceled
|
|
|
(199,857
|
)
|
|
|
11.92
|
|
|
Outstanding at December 31, 2014
|
|
|
4,789,622
|
|
|
$
|
12.85
|
|
|
Expected to vest in the future as of December 31, 2014
|
|
|
4,712,501
|
|
|
|
|
|
|
| Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] |
|
|
|
Year Ended December 31,
|
|
|
|
|
2014
|
|
|
2013
|
|
|
2012
|
|
|
Risk-free interest rate
|
|
|
0.07
|
%
|
|
|
0.10
|
%
|
|
|
0.13
|
%
|
|
Expected life (in years)
|
|
|
0.50
|
|
|
|
0.49
|
|
|
|
0.50
|
|
|
Dividend yield
|
|
|
—
|
|
|
|
—
|
|
|
|
—
|
|
|
Expected volatility
|
|
|
40
|
%
|
|
|
45
|
%
|
|
|
81
|
%
|
|
Estimated fair value
|
|
$
|
3.55
|
|
|
$
|
2.86
|
|
|
$
|
4.69
|
|
|
| Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] |
|
|
|
Year Ended December 31,
|
|
|
|
|
2014
|
|
|
2013
|
|
|
2012
|
|
|
Cost of revenue
|
|
$
|
1,260
|
|
|
$
|
1,086
|
|
|
$
|
726
|
|
|
Research and development
|
|
|
12,420
|
|
|
|
8,586
|
|
|
|
5,833
|
|
|
Sales and marketing
|
|
|
4,079
|
|
|
|
3,204
|
|
|
|
2,660
|
|
|
General and administrative
|
|
|
4,701
|
|
|
|
4,102
|
|
|
|
3,240
|
|
|
|
|
$
|
22,460
|
|
|
$
|
16,978
|
|
|
$
|
12,459
|
|
|