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

No definition available.

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Namespace Prefix:	gnty_
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Balance Type:	credit
Period Type:	duration

- Definition

Loan basis points.

+ References

No definition available.

+ Details

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- Definition

Loans classified in doubtful and loss risk rating.

+ References

No definition available.

+ Details

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Namespace Prefix:	gnty_
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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- 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 http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524

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- 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 http://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 http://asc.fasb.org/extlink&oid=121586364&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 http://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 http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

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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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LOANS AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) contract	Jun. 30, 2020 USD ($) contract	Dec. 31, 2020 USD ($) contract
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses provision	$ (1,000,000)	$ 12,100,000	$ (1,000,000)	$ 13,500,000
Loan basis points			14.00%
Loans classified in doubtful or loss risk rating	0		$ 0
Number of loans modified as TDRs \| contract			1	0	4
Increase in allowance for loan losses due to TDRs			$ 0		$ 0
Troubled debt restructuring charge-offs			$ 0		0
Provision for Other Credit Losses	$ 1,000,000.0
COVID-19
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses provision					$ 13,200,000