Loans and Allowance for Loan Losses - Summary of Nonperforming Loan Portfolio (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment, With related allowance	$ 114,741	$ 27,078	$ 114,741	$ 27,078	$ 62,493
Unpaid principal balance, With related allowance	115,027	27,733	115,027	27,733	62,964
Related allowance, With related allowance	58,008	3,420	58,008	3,420	15,156
Average investment recorded, With related allowance	113,759	29,964	114,383	25,272
Interest income recognized, With related allowance	288	217	1,469	728
Recreation [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment, With related allowance	6,569	6,708	6,569	6,708	8,262
Unpaid principal balance, With related allowance	6,569	6,708	6,569	6,708	8,262
Related allowance, With related allowance	229	256	229	256	329
Average investment recorded, With related allowance	6,730	6,687	6,882	6,921
Interest income recognized, With related allowance	167	152	428	366
Home Improvement [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment, With related allowance	103	239	103	239	185
Unpaid principal balance, With related allowance	103	239	103	239	185
Related allowance, With related allowance	2	4	2	4	3
Average investment recorded, With related allowance	103	243	103	245
Interest income recognized, With related allowance		2	2	2
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment, With related allowance	16,771	12,031	16,771	12,031	11,862
Unpaid principal balance, With related allowance	16,776	12,126	16,776	12,126	11,867
Average investment recorded, With related allowance	16,894	9,616	17,002	6,827
Interest income recognized, With related allowance		36	47	321
Medallion [Member]
Financing Receivable, Recorded Investment [Line Items]
Recorded Investment, With related allowance	91,298	8,100	91,298	8,100	42,184
Unpaid principal balance, With related allowance	91,579	8,660	91,579	8,660	42,650
Related allowance, With related allowance	57,777	3,160	57,777	3,160	$ 14,824
Average investment recorded, With related allowance	90,032	13,418	90,396	11,279
Interest income recognized, With related allowance	$ 121	$ 27	$ 992	$ 39

Impaired financing receivable with related allowance interest income and adjusted interest expense accrual method.

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- Definition

Impaired Financing Receivables With Related Allowance Related Allowance

+ References

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- Definition

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+ References

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- Definition

Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5212-111524

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5258-111524

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- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953550-111524

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