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STOCKHOLDERS' EQUITY - EQUITY PLANS (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
STOCKHOLDERS' EQUITY |  |  |
Exercise price as a percentage of fair market value | 85.00% |  |
Shares Available For Grant |  |  |
Balance at the beginning of the period (in shares) | 13,384,883 |  |
Options granted (in shares) | (2,875,000) |  |
Awards granted (in shares) | (14,015) |  |
Options canceled/forfeited (in shares) | 1,558,423 |  |
Awards canceled/forfeited (in shares) | 625 |  |
Balance at the end of the period (in shares) | 12,054,916 | 13,384,883 |
Number of Shares |  |  |
Balance at the beginning of the period (in shares) | 16,958,944 |  |
Options granted (in shares) | 2,875,000 |  |
Options exercised (in shares) | (1,069,838) |  |
Options canceled/forfeited (in shares) | (1,558,423) |  |
Balance at the end of the period (in shares) | 17,205,683 | 16,958,944 |
Options exercisable at the end of the period (in shares) | 11,356,232 | 9,129,576 | 8,144,040
Options fully vested and expected to vest at the end of the period (in shares) | 16,703,236 |  |
Weighted Average Exercise Price Per Share |  |  |
Balance at the beginning of the period (in dollars per share) | $ 3.16 |  |
Options granted (in dollars per share) | 4.29 |  |
Options exercised (in dollars per share) | 2.06 |  |
Options canceled/forfeited (in dollars per share) | 4.65 |  |
Balance at the end of the period (in dollars per share) | 3.29 | $ 3.16 |
Options exercisable at the end of the period (in dollars per share) | 2.98 | $ 3.12 | $ 4.26
Options fully vested and expected to vest at the end of the period (in dollars per share) | $ 3.26 |  |
Weighted Average Remaining Contractual Life (In years) |  |  |
Balance at the end of the period | 6 years 10 months 21 days |  |
Options exercisable at the end of the period | 6 years 2 months 5 days |  |
Options fully vested and expected to vest at the end of the period | 6 years 10 months 2 days |  |
Aggregate Intrinsic Value |  |  |
Balance at the end of the period (in dollars) | $ 29,267,000 | $ 16,038,000 |
Options exercisable at the end of the period (in dollars) | 23,234,000 |  |
Options fully vested and expected to vest at the end of the period (in dollars) | $ 28,932,000 |  |
Closing stock price (in dollars per share) | $ 4.84 |  |
Total pretax intrinsic value of stock options exercised (in dollars) | $ 2,398,000 | 989,000 | $ 2,787,000
Cash received from exercise of options (in dollars) | $ 2,205,000 | $ 1,286,000 | $ 6,567,000
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 |  |
Exercise price as a percentage of fair market value | 100.00% |  |
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) | 12,054,916 |  |
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) | 70,000 |  |
2011 Plan | Subsequent Director Option |  |  |
STOCKHOLDERS' EQUITY |  |  |
Options to be granted to purchase shares (in shares) | 35,000 |  |
1996 Directors Plan |  |  |
STOCKHOLDERS' EQUITY |  |  |
Vesting period of options | 3 years |  |
Percentage of option vesting | 100.00% |  |
1996 Directors Plan | Maximum |  |  |
STOCKHOLDERS' EQUITY |  |  |
Expiration term of options from date of grant | 10 years |  |
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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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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