Recently Issued Accounting Standards - Schedule of Impact of ASC 326 (Detail) $ in Thousands	Jan. 01, 2020 USD ($)
Off Balance Sheet Credit [Member]
Liabilities:
Allowance for credit losses on OBS exposures	$ 6,084
Residential Real Estate [Member]
ASSETS
Loans non-PCD	15,669
Loans PCD	3,021
Commercial Real Estate [Member]
ASSETS
Loans non-PCD	54,148
Loans PCD	11,966
Land, Development, Construction [Member]
ASSETS
Loans non-PCD	9,251
Loans PCD	256
Commercial and Industrial [Member]
ASSETS
Loans non-PCD	14,277
Loans PCD	1,924
Consumer and Other [Member]
ASSETS
Loans non-PCD	4,688
Loans PCD	63
Municipal Securities [Member]
ASSETS
Allowance for credit losses on debt securities held to maturity	10
Pre-ASC 326 Adoption [Member] \| Residential Real Estate [Member]
ASSETS
Loans non-PCD	4,257
Pre-ASC 326 Adoption [Member] \| Commercial Real Estate [Member]
ASSETS
Loans non-PCD	18,552
Pre-ASC 326 Adoption [Member] \| Land, Development, Construction [Member]
ASSETS
Loans non-PCD	2,319
Loans PCD	177
Pre-ASC 326 Adoption [Member] \| Commercial and Industrial [Member]
ASSETS
Loans non-PCD	11,282
Pre-ASC 326 Adoption [Member] \| Consumer and Other [Member]
ASSETS
Loans non-PCD	4,019
Loans PCD	49
Impact of ASC 326 Adoption [Member] \| Off Balance Sheet Credit [Member]
Liabilities:
Allowance for credit losses on OBS exposures	6,084
Impact of ASC 326 Adoption [Member] \| Residential Real Estate [Member]
ASSETS
Loans non-PCD	11,412
Loans PCD	3,021
Impact of ASC 326 Adoption [Member] \| Commercial Real Estate [Member]
ASSETS
Loans non-PCD	35,596
Loans PCD	11,966
Impact of ASC 326 Adoption [Member] \| Land, Development, Construction [Member]
ASSETS
Loans non-PCD	6,932
Loans PCD	79
Impact of ASC 326 Adoption [Member] \| Commercial and Industrial [Member]
ASSETS
Loans non-PCD	2,995
Loans PCD	1,924
Impact of ASC 326 Adoption [Member] \| Consumer and Other [Member]
ASSETS
Loans non-PCD	669
Loans PCD	14
Impact of ASC 326 Adoption [Member] \| Municipal Securities [Member]
ASSETS
Allowance for credit losses on debt securities held to maturity	$ 10

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Amount of increase from purchase of debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 11
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919244-210447

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Amount of allowance for credit loss at acquisition date of investment in debt security measured at amortized cost (held-to-maturity), purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 19
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447

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Amount at purchase price of investment in debt security measured at amortized cost (held-to-maturity), purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 19
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919265-210447

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118955202&loc=SL82895884-210446

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(7)(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447

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