Funds Borrowed - Schedule of Outstanding Balances of Funds Borrowed (Parenthetical) (Detail) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Debt Disclosure [Abstract]
Deferred costs	$ 8.5	$ 8.2
Reserve deposits	4.6	3.0
Retail savings deposit balance	$ 4.6	$ 6.0

The aggregate amount of all retail deposit accounts including demand accounts, savings accounts, and certificates of deposit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(12))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Name:	us-gaap_DepositsRetail
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant