SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue recognition (Details) |
12 Months Ended |
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Dec. 31, 2017 | |
| Other revenue - licensing fees from authorized test centers | |
| Revenue recognition | |
| Licensing period (in years) | 10 years |
| Test development services | Minimum | |
| Revenue recognition | |
| Period for development of tests | 2 months |
| Test development services | Maximum | |
| Revenue recognition | |
| Period for development of tests | 6 months |
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- Definition Represents period for development of tests. No definition available.
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- Definition Term of licensing period for authorized test centers, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. No definition available.
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