Additional reverse provision for signinficant improvements in COVID

No definition available.

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Namespace Prefix:	gnty_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Adjustments to qualitative factors results to provision for loan and lease losses.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Financing receivables, impaired, troubled debt restructuring, increase in allowance for loan losses.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Loans classified in doubtful and loss risk rating.

+ References

No definition available.

+ Details

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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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Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953676-111524

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Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953682-111524

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the amount of the write-down related to a troubled debt restructuring.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=121585226&loc=d3e18845-111554

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953423-111524

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of expense related to credit loss from transactions other than loan and lease transactions.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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LOANS AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Sep. 30, 2022 USD ($) Contract	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) Contract	Dec. 31, 2020 USD ($)
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses provision	$ 600,000		$ (700,000)			$ (650,000)	$ (1,700,000)
Additional reverse provision		$ 1,250,000
Loans classified in doubtful or loss risk rating	0					$ 0		$ 0
Number of loans modified as TDRs \| Contract						0		1
Number of contracts TDRS, subsequent default \| Contract						4
Increase in allowance for loan losses due to TDRs						$ 0		$ 0
Troubled debt restructuring charge-offs						$ 0		$ 0
COVID-19
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses provision									$ 13,200,000
Provision for Other Credit Losses			$ 700,000	$ 1,000,000	$ 0
Adjustments to qualitative factors results to provision for loan and lease losses	$ 600,000