Fair Value - Schedule of Difference between the Aggregate Fair Value and the Aggregate Remaining Principal Balance (Detail) - Residential loans held for sale - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Option, Quantitative Disclosures [Line Items]
Aggregate Fair Value	$ 85,091	$ 46,898
Difference	5,203	1,529
Contractual Principal	$ 79,888	$ 45,369

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of loans and long-term receivables (other than securities categorized as trading, available-for-sale or held-to-maturity) that have contractual principal amounts and for which the fair value option has been elected.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The face amount of loans that will be sold to other entities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

+ Details

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

- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

No definition available.

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: