Loans Held for Sale - Additional Information (Detail) - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Loans Receivables Held For Sale Net [Abstract]
Loans held for sale	$ 47,721,000	$ 83,969,000	$ 101,055,000
Loans held-for-sale at the lower of cost or fair value	$ 1,640,000	$ 4,384,000	$ 6,389,000

Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124265262&loc=d3e48678-111004

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