XML 85 R74.htm IDEA: XBRL DOCUMENT
v3.20.2

REGULATORY MATTERS - Narrative (Details) - USD ($) | Sep. 30, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | --- | --- | --- | ---
Common equity tier 1 capital to risk-weighted assets: |  |  |  |  |  |
Capital conservation buffer percentage, increase |  |  | 0.625% | 0.625% | 0.625% |
Subordinated debentures | Subordinated Debentures II, Subordinated Debentures III, and DCB Debentures I |  |  |  |  |  |
Common equity tier 1 capital to risk-weighted assets: |  |  |  |  |  |
Debenture issued | $ 10,310,000 | $ 10,310,000 |  |  |  |
Minimum |  |  |  |  |  |
Common equity tier 1 capital to risk-weighted assets: |  |  |  |  |  |
Capital conservation buffer percentage |  |  |  |  |  | 0.625%
Maximum |  |  |  |  |  |
Common equity tier 1 capital to risk-weighted assets: |  |  |  |  |  |
Capital conservation buffer percentage |  |  | 2.50% |  |  |

X
- Definition Annual increase in capital conservation buffer percentage. + References No definition available. + Details
Name: | gnty_AnnualIncreaseInCapitalConservationBufferPercentage
Namespace Prefix: | gnty_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Capital conservation buffer percentage. + References No definition available. + Details
Name: | gnty_CapitalConservationBufferPercentage
Namespace Prefix: | gnty_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_CommonEquityTierOneCapitalAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SubordinatedDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gnty_SubordinatedDebenturesIISubordinatedDebenturesIIIAndDCBDebenturesIMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |