Securities Owned - Schedule of Securities Owned/Sold But Not Yet Purchased (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Security Owned and Sold Not yet Purchased, at Fair Value [Line Items]
Securities Owned Total	$ 125,110	$ 127,166
Trading Securities [Member]
Security Owned and Sold Not yet Purchased, at Fair Value [Line Items]
Securities Owned Total	$ 125,110	$ 127,166

Fair value of financial instruments held by a broker-dealer for their own account (proprietary securities) for trading or investment purposes determined by management based upon quoted prices of a financial instrument with similar characteristics or on a valuation technique or model.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969

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