SHARE BASED COMPENSATION - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares exercisable (in shares)	2,400,000
Weighted average exercise price (in dollars per share)	$ 13.47
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unamortized stock compensation expense	$ 40,800
Weighted-average recognition period (in years)	1 year 8 months 12 days
Shares Underlying Options
Beginning Balance (in shares)	5,665,584
Granted (in shares)	55,000
Exercised (in shares)	(85,750)
Forfeited/canceled (in shares)	(93,993)
Ending Balance (in shares)	5,540,841	5,665,584
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 17.05
Granted (in dollars per share)	15.16
Exercised (in dollars per share)	9.11
Forfeited/canceled (in dollars per share)	19.62
Ending balance (in dollars per share)	$ 17.11	$ 17.05
Weighted Average Remaining Contractual Life (years)	8 years 5 months 1 day	8 years 9 months
Aggregate Intrinsic Value (in thousands)	$ 11,305	$ 31,542

Unrecognized cost of unvested share-based compensation awards.

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-Publisher FASB
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-Topic 718
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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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.

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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.

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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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