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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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STOCK-BASED COMPENSATION, Stock-Based Compensation - Additional Information (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Jan. 11, 2012	Dec. 31, 2014
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Options granted	2,069,300
Underlying options, in shares	30,246
Stock Options
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Unrecognized compensation cost, net of forfeitures	81,547
Weighted average remaining contractual term, exercisable	6 years 1 month 17 days
Weighted average remaining contractual term, outstanding	9 years
Total unrecognized compensation cost related to non-vested share-based compensation awards granted, period for recognition	2 years 5 months 5 days
Restricted Stock
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Stock options issued (in shares)	48,000
Underlying service-based awards, unvested and outstanding (in shares)	660,000		633,442
Service-Based Awards
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Total unrecognized compensation cost related to non-vested share-based compensation awards granted	15,748
Total unrecognized compensation cost related to non-vested share-based compensation awards granted, period for recognition	1 year 9 months 21 days
Underlying service-based awards, unvested and outstanding (in shares)	544,692
Underlying options, value at grant date	25,176
Performance-Based Awards
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Total unrecognized compensation cost related to non-vested share-based compensation awards granted	14,898
Total unrecognized compensation cost related to non-vested share-based compensation awards granted, period for recognition	1 year 10 months 2 days
Stock options issued (in shares)	0
Underlying service-based awards, unvested and outstanding (in shares)	342,426		371,510
2012 Directors Plan
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Shares authorized to be reserved for issuance (in shares)		600,000
2012 Directors Plan expiration period		10 years
Common stock shares available for issuance (in shares)	559,365
2012 Directors Plan \| Restricted Stock
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Non-vested common stock shares issued (in shares)	0
Total unrecognized compensation cost related to non-vested share-based compensation awards granted	205
Total unrecognized compensation cost related to non-vested share-based compensation awards granted, period for recognition	1 year 9 months
2012 Plan
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Common stock shares available for issuance (in shares)	2,702,383
2012 Plan \| Stock Options
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Options granted	2,069,300
Aggregate grant-date fair value of stock options	43,992
2012 Plan \| Restricted Stock Units (RSUs)
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Total unrecognized compensation cost related to non-vested share-based compensation awards granted	4,450
Total unrecognized compensation cost related to non-vested share-based compensation awards granted, period for recognition	2 years 7 months
Deferred compensation, shares issued	48,000
Deferred compensation arrangement, fair value of shares issued	2,946
Vesting percentage	25.00%
2006 Plan
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Common stock shares subject to outstanding awards that expire or terminate that are available for awards to be granted (in shares)	1,542,847
2006 Plan \| Stock Options
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Options issued expiration period	10 years