Preferred Stock and Stockholders' Equity (Summary of Stock Plan Activity) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands |
12 Months Ended |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Shares Available For Future Grant |
|
|
|
| Beginning balance |
7,546
|
4,926
|
4,055
|
| Increase in shares authorized for grant |
4,056
|
3,993
|
3,992
|
| Shares granted |
(4,902)
|
(2,140)
|
(3,565)
|
| Shares cancelled and forfeited |
1,370
|
767
|
444
|
| Ending balance |
8,070
|
7,546
|
4,926
|
| Shares Subject to Options Outstanding |
|
|
|
| Beginning balance |
14,704
|
14,712
|
11,626
|
| Shares granted |
4,902
|
2,140
|
3,565
|
| Shares exercised |
(2,041)
|
(1,381)
|
(35)
|
| Shares expired |
|
|
(444)
|
| Shares cancelled and forfeited |
(1,370)
|
(767)
|
|
| Ending balance |
16,195
|
14,704
|
14,712
|
| Options exercisable |
10,639
|
|
|
| Options fully vested and expected to vest |
16,195
|
|
|
| Outstanding Options, Weighted- Average Exercise Price |
|
|
|
| Beginning balance |
$ 2.62
|
$ 2.63
|
$ 2.90
|
| Shares granted |
3.88
|
2.62
|
1.98
|
| Shares exercised |
2.55
|
1.34
|
1.58
|
| Shares expired |
|
|
4.58
|
| Shares cancelled and forfeited |
3.07
|
5.03
|
|
| Ending balance |
2.98
|
$ 2.62
|
$ 2.63
|
| Options exercisable |
2.71
|
|
|
| Options fully vested and expected to vest |
$ 2.98
|
|
|
| Outstanding Options, Weighted Average Remaining Contractual Life |
|
|
|
| Weighted average remaining contractual life |
6 years 4 months 6 days
|
|
|
| Weighted average remaining contractual life, Options exercisable |
5 years 11 days
|
|
|
| Weighted average remaining contractual life, Options fully vested and expected to vest |
6 years 4 months 6 days
|
|
|
| Outstanding Options, Aggregate Intrinsic Value |
|
|
|
| Aggregate Intrinsic Value |
$ 33,318
|
|
|
| Options exercisable |
24,250
|
|
|
| Options fully vested and expected to vest |
$ 33,318
|
|
|