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STOCK BASED COMPENSATION - Summary of Assumptions (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Principal assumptions used in applying the Black-Scholes option pricing model for the awards |  |  |
Risk-free interest rate (as a percent) |  |  | 1.10%
Volatility factor of the expected market price of common stock (as a percent) | 74.00% |  | 70.00%
Weighted-average expected life of option | 5 years | 5 years | 3 years 6 months
Weighted-average grant date fair value (in dollars per share) | $ 2.36 | $ 0.49 | $ 1.45
Risk-free interest rate, low end of range (as a percent) | 1.13% | 1.10% |
Risk-free interest rate, high end of range (as a percent) | 1.21% | 1.79% |
Additional disclosures |  |  |
Stock option expense | $ 1,000 | $ 1,300 | $ 1,300
Fair value of awards vesting in the period | 1,300 | 1,500 | 2,000
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount | 0 | 0 | 0
Unrecognized compensation expense on non-vested stock options (in dollars) | $ 1,400 | $ 1,600 | $ 1,800
Non-vested stock options outstanding (in shares) | 2.5 | 4.2 | 2.7
Weighted-average period of recognition | 1 year 7 months 6 days | 1 year 7 months 6 days | 1 year 7 months 6 days
Minimum |  |  |
Principal assumptions used in applying the Black-Scholes option pricing model for the awards |  |  |
Dividend yield (as a percent) | 0.24% | 0.00% |
Volatility factor of the expected market price of common stock, low end of range (as a percent) |  | 73.00% |
Maximum |  |  |
Principal assumptions used in applying the Black-Scholes option pricing model for the awards |  |  |
Dividend yield (as a percent) | 0.27% | 1.15% |
Volatility factor of the expected market price of common stock, high end of range (as a percent) |  | 74.00% |

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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + 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 (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the 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 (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References No definition available. + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own 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 (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The maximum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
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- Definition The minimum risk-free interest rate assumption that is used in valuing an option on its own shares. + References No definition available. + Details
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- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + 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 (f)(2)(i) -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 S99 -Paragraph 1 -Subparagraph (SAB Topic 14.D.2) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 + Details
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