Fair Value Disclosures - Schedule of Gain Loss on Sale of Mortgage Loans (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule Of Gain Loss On Sale Of Mortgage Loans [Abstract]
Realized gain on sale and fees on mortgage loans	$ 9,050	$ 13,494	$ 29,245	$ 25,676
Change in fair value on loans held-for-sale and IRLCs	(1,466)	1,508	(4,659)	7,800
Change in forward mortgage-backed securities trades	1,204	226	2,387	(720)
Total gain on sale of mortgage loans	$ 8,788	$ 15,228	$ 26,973	$ 32,756

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123605502&loc=d3e21310-158488

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123605502&loc=d3e21286-158488

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123605549&loc=d3e21493-158490

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