XML 94 R81.htm IDEA: XBRL DOCUMENT
v3.24.0.1

EMPLOYEE BENEFITS - Pension Plan Asset Categories (Details) - USD ($) $ in Thousands | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | --- | --- | ---
Retirement Plan |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets |  | $ 81,551 | $ 76,735 | $ 97,439 | $ 90,419
Retirement Plan Acquired |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets |  | 3,085 | 3,128 | $ 3,871 | $ 3,613
Level 1 | Retirement Plan | Cash |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets |  | 1,428 | 605 |  |
Level 1 | Retirement Plan | U.S. large cap equities |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [1] | 28,506 | 23,032 |  |
Level 1 | Retirement Plan | U.S. mid cap equities |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [2] | 4,323 | 3,594 |  |
Level 1 | Retirement Plan | U.S. small cap equities |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [3] | 11,907 | 12,447 |  |
Level 1 | Retirement Plan | International |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [4] | 0 | 0 |  |
Level 1 | Retirement Plan | Corporate bonds |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 0 | 0 |  |
Level 1 | Retirement Plan | International developed |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [6] | 9,317 | 8,161 |  |
Level 1 | Retirement Plan | International emerging |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [2] | 1,964 | 1,841 |  |
Level 1 | Retirement Plan | Real estate |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [7] | 0 | 0 |  |
Level 1 | Retirement Plan | US Treasury and Government |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 148 | 233 |  |
Level 1 | Retirement Plan Acquired | Cash |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets |  | 0 | 0 |  |
Level 1 | Retirement Plan Acquired | U.S. large cap equities |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [1] | 1,055 | 1,103 |  |
Level 1 | Retirement Plan Acquired | U.S. mid cap equities |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [2] | 125 | 135 |  |
Level 1 | Retirement Plan Acquired | U.S. small cap equities |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [3] | 64 | 66 |  |
Level 1 | Retirement Plan Acquired | International |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [4] | 540 | 547 |  |
Level 1 | Retirement Plan Acquired | Corporate bonds |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 1,078 | 1,027 |  |
Level 1 | Retirement Plan Acquired | International developed |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [6] | 0 | 0 |  |
Level 1 | Retirement Plan Acquired | International emerging |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [2] | 0 | 0 |  |
Level 1 | Retirement Plan Acquired | Real estate |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [7] | 223 | 250 |  |
Level 1 | Retirement Plan Acquired | US Treasury and Government |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 0 | 0 |  |
Level 2 | Retirement Plan | Cash equivalents |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets |  | 5,957 | 8,543 |  |
Level 2 | Retirement Plan | Corporate bonds |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 1,893 | 1,979 |  |
Level 2 | Retirement Plan | U.S. government agencies |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 4,871 | 4,380 |  |
Level 2 | Retirement Plan | Municipal bonds |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 11,119 | 11,774 |  |
Level 2 | Retirement Plan | U.S. agency mortgage-backed securities |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [8] | 118 | 146 |  |
Level 2 | Retirement Plan Acquired | Cash equivalents |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets |  | 0 | 0 |  |
Level 2 | Retirement Plan Acquired | Corporate bonds |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 0 | 0 |  |
Level 2 | Retirement Plan Acquired | U.S. government agencies |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 0 | 0 |  |
Level 2 | Retirement Plan Acquired | Municipal bonds |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [5] | 0 | 0 |  |
Level 2 | Retirement Plan Acquired | U.S. agency mortgage-backed securities |  |  |  |  |
Defined Benefit Plan, Categories of Plan Assets [Abstract] |  |  |  |  |
Total fair value of plan assets | [8] | $ 0 | $ 0 |  |
[1] | For the Retirement Plan, this category is comprised of broadly diversified “passive” and “active” mutual funds. The Acquired Retirement Plan assets in this category consist of pooled separate accounts invested in mutual funds and domestic stocks.
[2] | For the Retirement Plan, this category is comprised of broadly diversified “active” mutual funds. The Acquired Retirement Plan assets in this category consist of pooled separate accounts invested in mutual funds.
[3] | For the Retirement Plan, this category is comprised of broadly diversified “passive” and “active” mutual funds and shares of Southside Bancshares stock. The Acquired Retirement Plan assets in this category consist of pooled separate accounts invested in mutual funds.
[4] | This category is comprised of pooled separate accounts invested in mutual funds and international stocks.
[5] | For the Retirement Plan, this category is comprised of individual investment grade securities that are generally HTM. The Acquired Retirement Plan assets in this category consist of pooled separate accounts invested in mutual funds, bonds and fixed income securities.
[6] | This category is comprised of a broadly diversified “passive” and “active” mutual funds.
[7] | This category is comprised of a pooled separate account invested in commercial real estate and includes mortgage loans which are backed by the associated properties.
[8] | This category is comprised of individual securities that are generally not HTM.

X
- Definition Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CashMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sbsi_UnitedStatesLargeCapEquitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sbsi_UnitedStatesMidCapEquitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sbsi_UnitedStatesSmallCapEquitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sbsi_InternationalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CorporateBondSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sbsi_InternationalDevelopedEquitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sbsi_InternationalEmergingEquitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_RealEstateFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_CashEquivalentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |