FAIR VALUE MEASUREMENTS - Financial Assets and Liabilities at Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Liabilities, Fair Value Disclosure [Abstract]
Transfers Into Level 3	$ 0	$ 0
Transfers out of Level 3	0	$ 0
Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	244,877		$ 199,449
Time deposits and restricted cash	238		30,419
Employee loans	5,885		6,338
Total assets measured at fair value	251,000		236,206
Liabilities, Fair Value Disclosure [Abstract]
Performance-based equity awards	6,849		5,364
Total liabilities measured at fair value on a recurring basis	6,924		5,364
Fair Value, Measurements, Recurring \| Cash-Settled Award \| Restricted Stock Units
Liabilities, Fair Value Disclosure [Abstract]
Cash-settled restricted stock units	75
Fair Value, Measurements, Recurring \| Level 1
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	244,877		199,449
Time deposits and restricted cash	0		0
Employee loans	0		0
Total assets measured at fair value	244,877		199,449
Liabilities, Fair Value Disclosure [Abstract]
Performance-based equity awards	0		0
Total liabilities measured at fair value on a recurring basis	75		0
Fair Value, Measurements, Recurring \| Level 1 \| Cash-Settled Award \| Restricted Stock Units
Liabilities, Fair Value Disclosure [Abstract]
Cash-settled restricted stock units	75
Fair Value, Measurements, Recurring \| Level 2
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0		0
Time deposits and restricted cash	238		30,419
Employee loans	0		0
Total assets measured at fair value	238		30,419
Liabilities, Fair Value Disclosure [Abstract]
Performance-based equity awards	0		0
Total liabilities measured at fair value on a recurring basis	0		0
Fair Value, Measurements, Recurring \| Level 2 \| Cash-Settled Award \| Restricted Stock Units
Liabilities, Fair Value Disclosure [Abstract]
Cash-settled restricted stock units	0
Fair Value, Measurements, Recurring \| Level 3
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	0		0
Time deposits and restricted cash	0		0
Employee loans	5,885		6,338
Total assets measured at fair value	5,885		6,338
Liabilities, Fair Value Disclosure [Abstract]
Performance-based equity awards	6,849		5,364
Total liabilities measured at fair value on a recurring basis	6,849		$ 5,364
Fair Value, Measurements, Recurring \| Level 3 \| Cash-Settled Award \| Restricted Stock Units
Liabilities, Fair Value Disclosure [Abstract]
Cash-settled restricted stock units	$ 0

Fair value portion of liabilities for stock option plans and other equity-based compensation arrangements.

No definition available.

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- Definition

Fair value portion of cash and cash equivalent items which are restricted as to withdrawal or usage and time deposits

+ References

No definition available.

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- References

No definition available.

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- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a recurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

No definition available.

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

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- Definition

Fair value of equity issued in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

Amount of transfers of financial instrument classified as a liability into level 3 of the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- References

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- Definition

Aggregation of the liabilities reported on the balance sheet measured at fair value on a recurring basis by the entity.

+ References

No definition available.

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- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Glossary Loan
-URI http://asc.fasb.org/extlink&oid=6517073

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