XML 38 R29.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands | Sep. 30, 2022 | Dec. 31, 2021
--- | --- | ---
ASSETS |  |
Available-for-sale debt securities | $ 996,403 | $ 909,651
Marketable equity securities | 1,025 | 1,142
Derivative financial assets | 88,896 | 33,933
LIABILITIES |  |
Derivative financial liabilities | 111,647 | 33,631
U.S. Treasury securities |  |
ASSETS |  |
Available-for-sale debt securities | 120,825 | 95,327
Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 51,784 | 70,348
Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 419,719 | 270,294
Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 41,984 | 56,793
Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 323,469 | 341,300
Obligations of states and political subdivisions |  |
ASSETS |  |
Available-for-sale debt securities | 38,122 | 75,089
Fair Value Measurements, Recurring |  |
ASSETS |  |
Available-for-sale debt securities | 996,403 | 909,651
Marketable equity securities | 1,025 | 1,142
Total Securities | 997,428 | 910,793
Securities held in a deferred compensation plan | 7,354 | 10,230
Total Assets | 1,093,678 | 954,956
LIABILITIES |  |
Total Liabilities | 111,647 | 33,631
Fair Value Measurements, Recurring | U.S. Treasury securities |  |
ASSETS |  |
Available-for-sale debt securities | 120,825 | 95,327
Fair Value Measurements, Recurring | Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 51,784 | 70,348
Fair Value Measurements, Recurring | Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 419,719 | 270,294
Fair Value Measurements, Recurring | Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 41,984 | 56,793
Fair Value Measurements, Recurring | Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 323,469 | 341,300
Fair Value Measurements, Recurring | Corporate obligations |  |
ASSETS |  |
Available-for-sale debt securities | 500 | 500
Fair Value Measurements, Recurring | Obligations of states and political subdivisions |  |
ASSETS |  |
Available-for-sale debt securities | 38,122 | 75,089
Fair Value Measurements, Recurring | Interest rate swaps - commercial loans |  |
ASSETS |  |
Derivative financial assets | 88,888 | 33,528
LIABILITIES |  |
Derivative financial liabilities | 88,920 | 33,631
Fair Value Measurements, Recurring | Forward sale contracts - mortgage loans |  |
ASSETS |  |
Derivative financial assets | 8 | 4
Fair Value Measurements, Recurring | Interest rate lock commitments |  |
ASSETS |  |
Derivative financial assets |  | 401
LIABILITIES |  |
Derivative financial liabilities | 3 |
Fair Value Measurements, Recurring | Interest rate swaps - cash flow hedge |  |
LIABILITIES |  |
Derivative financial liabilities | 22,724 |
Fair Value Measurements, Recurring | Level 1 |  |
ASSETS |  |
Available-for-sale debt securities | 120,825 | 95,327
Marketable equity securities | 963 | 1,061
Total Securities | 121,788 | 96,388
Securities held in a deferred compensation plan | 7,354 | 10,230
Total Assets | 129,142 | 106,618
LIABILITIES |  |
Total Liabilities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | U.S. Treasury securities |  |
ASSETS |  |
Available-for-sale debt securities | 120,825 | 95,327
Fair Value Measurements, Recurring | Level 1 | Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Corporate obligations |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Obligations of states and political subdivisions |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Interest rate swaps - commercial loans |  |
ASSETS |  |
Derivative financial assets | 0 | 0
LIABILITIES |  |
Derivative financial liabilities | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Forward sale contracts - mortgage loans |  |
ASSETS |  |
Derivative financial assets | 0 | 0
Fair Value Measurements, Recurring | Level 1 | Interest rate lock commitments |  |
ASSETS |  |
Derivative financial assets |  | 0
LIABILITIES |  |
Derivative financial liabilities | 0 |
Fair Value Measurements, Recurring | Level 1 | Interest rate swaps - cash flow hedge |  |
LIABILITIES |  |
Derivative financial liabilities | 0 |
Fair Value Measurements, Recurring | Level 2 |  |
ASSETS |  |
Available-for-sale debt securities | 875,578 | 814,324
Marketable equity securities | 62 | 81
Total Securities | 875,640 | 814,405
Securities held in a deferred compensation plan | 0 | 0
Total Assets | 964,528 | 847,933
LIABILITIES |  |
Total Liabilities | 111,644 | 33,631
Fair Value Measurements, Recurring | Level 2 | U.S. Treasury securities |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 2 | Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 51,784 | 70,348
Fair Value Measurements, Recurring | Level 2 | Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 419,719 | 270,294
Fair Value Measurements, Recurring | Level 2 | Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 41,984 | 56,793
Fair Value Measurements, Recurring | Level 2 | Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 323,469 | 341,300
Fair Value Measurements, Recurring | Level 2 | Corporate obligations |  |
ASSETS |  |
Available-for-sale debt securities | 500 | 500
Fair Value Measurements, Recurring | Level 2 | Obligations of states and political subdivisions |  |
ASSETS |  |
Available-for-sale debt securities | 38,122 | 75,089
Fair Value Measurements, Recurring | Level 2 | Interest rate swaps - commercial loans |  |
ASSETS |  |
Derivative financial assets | 88,888 | 33,528
LIABILITIES |  |
Derivative financial liabilities | 88,920 | 33,631
Fair Value Measurements, Recurring | Level 2 | Forward sale contracts - mortgage loans |  |
ASSETS |  |
Derivative financial assets | 0 | 0
Fair Value Measurements, Recurring | Level 2 | Interest rate lock commitments |  |
ASSETS |  |
Derivative financial assets |  | 0
LIABILITIES |  |
Derivative financial liabilities | 0 |
Fair Value Measurements, Recurring | Level 2 | Interest rate swaps - cash flow hedge |  |
LIABILITIES |  |
Derivative financial liabilities | 22,724 |
Fair Value Measurements, Recurring | Level 3 |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Marketable equity securities | 0 | 0
Total Securities | 0 | 0
Securities held in a deferred compensation plan | 0 | 0
Total Assets | 8 | 405
LIABILITIES |  |
Total Liabilities | 3 | 0
Fair Value Measurements, Recurring | Level 3 | U.S. Treasury securities |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Collateralized mortgage obligations of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Residential mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Commercial mortgage-backed securities of U.S. government corporations and agencies |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Corporate obligations |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Obligations of states and political subdivisions |  |
ASSETS |  |
Available-for-sale debt securities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Interest rate swaps - commercial loans |  |
ASSETS |  |
Derivative financial assets | 0 | 0
LIABILITIES |  |
Derivative financial liabilities | 0 | 0
Fair Value Measurements, Recurring | Level 3 | Forward sale contracts - mortgage loans |  |
ASSETS |  |
Derivative financial assets | 8 | 4
Fair Value Measurements, Recurring | Level 3 | Interest rate lock commitments |  |
ASSETS |  |
Derivative financial assets |  | $ 401
LIABILITIES |  |
Derivative financial liabilities | 3 |
Fair Value Measurements, Recurring | Level 3 | Interest rate swaps - cash flow hedge |  |
LIABILITIES |  |
Derivative financial liabilities | $ 0 |

X
- Definition Assets Held-in-Trust, Fair Value Disclosure + References No definition available. + Details
Name: | stba_AssetsHeldinTrustFairValueDisclosure
Namespace Prefix: | stba_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
Name: | us-gaap_DerivativeAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 + Details
Name: | us-gaap_DerivativeLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (f) -URI https://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 45 -Paragraph 1A -URI https://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740 + Details
Name: | us-gaap_EquitySecuritiesFvNi
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

X
- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258 + Details
Name: | us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentCorporationsAndAgenciesSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=stba_InterestRateSwapCommercialLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ForwardContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_InterestRateLockCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |