| BUSINESS COMBINATIONS (Details) - USD ($) | Apr. 24, 2020 | Aug. 22, 2019 | Mar. 31, 2021 | 
|---|---|---|---|
| April 2020 acquisition | |||
| Business Acquisition | |||
| Total purchase consideration | $ 11,400,000 | ||
| Acquired goodwill | $ 2,200,000 | ||
| August 2019 acquisition | |||
| Business Acquisition | |||
| Total purchase consideration | $ 94,000,000.0 | ||
| Additional consideration (up to) | 60,000,000.0 | ||
| Contingent consideration | $ 0 | ||
| August 2019 acquisition | Wafer Inspection and Patterning | |||
| Business Acquisition | |||
| Acquired goodwill | $ 54,200,000 | ||
| Other 2019 acquisitions | |||
| Business Acquisition | |||
| Contingent consideration | 7,400,000 | ||
| Contingent consideration liability, current | 600,000 | ||
| Contingent consideration liability, non-current | $ 6,800,000 | 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of liability recognized arising from contingent consideration in a business combination. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled beyond one year or the normal operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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