BASIS OF PRESENTATION AND ACCOUNTING POLICIES - Narrative (Details)	Mar. 31, 2021 USD ($) branch	Dec. 31, 2020 USD ($)	Mar. 26, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of branches operated \| branch	165
Cash reserve required rate			0.00%
Reserve requirement \| $	$ 0	$ 0

Cash deposited in a special reserve account for the exclusive benefit of customers pursuant to SEC Regulations.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116631393&loc=SL116631396-227033

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant