SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales and marketing	$ 2,339	$ 2,062	$ 1,754	$ 1,520	$ 1,599	$ 6,935
Technology and product development	5,389	4,513	4,425	3,783	3,214	15,935
General and administrative	7,264	7,677	7,552	8,528	11,997	35,754
Depreciation and amortization		996	991	1,052	1,068	4,107
Total operating expenses	$ 16,014	15,248	14,722	14,883	17,878	62,731
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling, general, and administrative		14,252	13,731	13,831	16,810	58,624
Depreciation and amortization		996	991	1,052	1,068	4,107
Total operating expenses		$ 15,248	$ 14,722	$ 14,883	$ 17,878	$ 62,731

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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