Loans Held for Investment and Allowance for Credit Losses on Loans - Summary of Loans Held for Investment by Portfolio Segment (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Receivables [Abstract]
Accrued interest receivable	$ 30.6	$ 21.0
Pay check protection program loan held for investment	1.1	80.4
Paycheck protection program unamortized processing fees	$ 0.0	$ 2.0

Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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