Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Feb. 28, 2022	May 31, 2021
Statement of Financial Position [Abstract]
Debt securities trading, at fair value, pledged as collateral	$ 0	$ 210,894

Fair value of securities pledged as collateral against securities sold under agreement to repurchase.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226013-175313

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