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STOCKHOLDERS' EQUITY - EQUITY PLANS (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 30, 2016
Shares Available For Grant |  |  |  |
Balance at the beginning of the period (in shares) | 12,054,916 |  |  |
Options granted (in shares) | (2,834,000) |  |  |
Awards granted (in shares) | (21,541) |  |  |
Options cancelled/forfeited (in shares) | 371,160 |  |  |
Balance at the end of the period (in shares) | 9,570,535 | 12,054,916 |  |
Number of Shares |  |  |  |
Balance at the beginning of the period (in shares) | 17,205,683 |  |  |
Options granted (in shares) | 2,834,000 |  |  |
Options exercised (in shares) | (328,486) |  |  |
Options cancelled/forfeited (in shares) | (585,910) |  |  |
Balance at the end of the period (in shares) | 19,125,287 | 17,205,683 |  |
Options exercisable at the end of the period (in shares) | 14,074,457 | 11,356,232 | 9,129,576 |
Options fully vested and expected to vest at the end of the period (in shares) | 18,694,300 |  |  |
Weighted Average Exercise Price Per Share |  |  |  |
Balance at the beginning of the period (in dollars per share) | $ 3.29 |  |  |
Options granted (in dollars per share) | 2.56 |  |  |
Options exercised (in dollars per share) | 1.50 |  |  |
Options cancelled/forfeited (in dollars per share) | 5.34 |  |  |
Balance at the end of the period (in dollars per share) | 3.15 | $ 3.29 |  |
Options exercisable at the end of the period (in dollars per share) | 2.99 | $ 2.98 | $ 3.12 |
Options fully vested and expected to vest at the end of the period (in dollars per share) | $ 3.14 |  |  |
Weighted Average Remaining Contractual Life (In years) |  |  |  |
Balance at the end of the period | 6 years 7 months 24 days |  |  |
Options exercisable at the end of the period | 6 years 18 days |  |  |
Options fully vested and expected to vest at the end of the period | 6 years 7 months 6 days |  |  |
Aggregate Intrinsic Value |  |  |  |
Balance at the end of the period (in dollars) | $ 3,816,000 |  |  |
Options exercisable at the end of the period (in dollars) | 3,718,000 |  |  |
Options fully vested and expected to vest at the end of the period (in dollars) | 3,815,000 |  |  |
Closing stock price (in dollars per share) |  |  |  | $ 2.07
Total pretax intrinsic value of stock options exercised (in dollars) | 595,000 | $ 2,398,000 | $ 989,000 |
Cash received from exercise of options (in dollars) | $ 493,000 | $ 2,205,000 | $ 1,286,000 |
2002 Plan |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Vesting period of options | 4 years |  |  |
Exercise price as a percentage of fair market value | 100.00% |  |  |
2002 Plan | Maximum |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Expiration term of options from date of grant | 10 years |  |  |
2011 Plan |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Vesting period of options | 4 years |  |  |
Minimum percentage of ownership required for granting options at least 110% of fair market value of common stock | 10.00% |  |  |
Minimum exercise price as a percentage of fair market value for employees having more than 10 % outstanding common stock | 110.00% |  |  |
Maximum expiration term of options granted to employees having more than 10 % outstanding common stock | 5 years |  |  |
Shares Available For Grant |  |  |  |
Balance at the end of the period (in shares) | 9,570,535 |  |  |
2011 Plan | Maximum |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Expiration term of options from date of grant | 10 years |  |  |
2011 Plan | First Director Option |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Vesting period of options | 3 years |  |  |
Options to be granted to purchase shares upon appointment (in shares) | 100,000 |  |  |
2011 Plan | Subsequent Director Option |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Options to be granted to purchase shares (in shares) | 50,000 |  |  |
2006 Directors Plan | Maximum |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Expiration term of options from date of grant | 10 years |  |  |
2006 Directors Plan | First Director Option |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Vesting period of options | 3 years |  |  |
2006 Directors Plan | Subsequent Director Option |  |  |  |
STOCKHOLDERS' EQUITY |  |  |  |
Vesting period of options | 1 year |  |  |

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