COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Commitments and Contingencies Disclosure [Abstract] | |||
| Rent expense | $ 9.7 | $ 7.8 | $ 6.6 |
| Sublease income | $ 0.7 | $ 0.6 | $ 0.5 |
| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition The amount of revenue recognized for the period under subleasing arrangements. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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