SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property, equipment, and intangible assets, net (Details)	12 Months Ended
Dec. 31, 2020
Electronic Equipment
Property, equipment, and intangible assets, net
Useful life (in years)	3 years
Office Equipment
Property, equipment, and intangible assets, net
Useful life (in years)	5 years
Software
Property, equipment, and intangible assets, net
Useful life (in years)	5 years

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration