RESTRICTED CASH - Schedule of restricted cash (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026
Cash and Cash Equivalents [Line Items]
Restricted cash	$ 1,473,196	$ 1,246,312
Allowance for restricted cash	(15,775)	(15,982)
Brokerage customers’ cash
Cash and Cash Equivalents [Line Items]
Restricted cash	1,303,828	1,095,026
Guaranty deposits
Cash and Cash Equivalents [Line Items]
Restricted cash	158,787	135,258
Short term placements
Cash and Cash Equivalents [Line Items]
Restricted cash	8,592	16,368
Restricted bank accounts
Cash and Cash Equivalents [Line Items]
Restricted cash	9,114	9,436
Due from banks
Cash and Cash Equivalents [Line Items]
Restricted cash	8,627	6,183
Deferred distribution payment
Cash and Cash Equivalents [Line Items]
Restricted cash	$ 23	$ 23

Amount of cash restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.