STOCK-BASED COMPENSATION (Details 3) (USD $)	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stockholders' Equity
Shares exercised			1,312,000
Weighted-average exercise price of shares exercised (in dollars per share)			$ 15.11
Total cash proceed			$ 19,834,000
Employee stock options
Weighted-average assumptions
Risk-free interest rate, minimum (as a percent)	1.68%	0.83%	0.76%	0.74%
Risk-free interest rate, maximum (as a percent)	2.02%	0.86%	2.02%	1.17%
Expected term	6 years	6 years
Volatility (as a percent)	60.00%	57.00%
Volatility, minimum (as a percent)			58.00%	55.00%
Volatility, maximum (as a percent)			60.00%	60.00%
Weighted-average estimated fair value of awards granted (in dollars per share)	$ 21.63	$ 14.31	$ 18.11	$ 11.41
Employee stock options \| Minimum
Weighted-average assumptions
Expected term			5 years	5 years
Employee stock options \| Maximum
Weighted-average assumptions
Expected term			6 years	6 years

The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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-Name Accounting Standards Codification

-Glossary Financing Activities

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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.

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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.

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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.

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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.

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The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Number of share options (or share units) exercised during the current period.

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