ORDINARY SHARE AND SHARE INCENTIVE PLANS - Unvested Restricted Awards - Additional Information (Details) - 2017 Equity Incentive Plan - Restricted Stock shares in Thousands, $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares
Restricted stock awards
Vesting period	4 years
Ratio for grant of stock awards that is deducted from the shares available for grant	1
Shares
Vested (in shares)	(536)	(494)
Fair value of restricted stock awards vested \| $	$ 1.5	$ 1.4
Granted (in shares)	76	407

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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.

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Represents the ratio for grant of stock awards that is deducted from the shares available for grant.

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