XML 76 R60.htm IDEA: XBRL DOCUMENT
v3.20.2

Allowance for Credit Losses - Collateral Dependent Loans by Class of Loan (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Jan. 01, 2020 | Dec. 31, 2019
--- | --- | --- | ---
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | $ 7,394,868 |  | $ 7,137,152
Real Estate |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 63,058 |  |
Blanket Lien |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 22,209 |  |
Investment/Cash |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Other |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 689 |  |
Commercial |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 5,810,034 |  | 5,512,796
Commercial | Commercial real estate |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 2,818,227 | $ 3,416,518 | 3,059,592
Commercial | Commercial real estate | Real Estate |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 46,965 |  |
Commercial | Commercial real estate | Blanket Lien |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 40 |  |
Commercial | Commercial real estate | Investment/Cash |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Commercial | Commercial real estate | Other |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Commercial | Commercial and industrial |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 1,818,649 | 1,720,833 | 1,480,529
Commercial | Commercial and industrial | Real Estate |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 6,065 |  |
Commercial | Commercial and industrial | Blanket Lien |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 20,548 |  |
Commercial | Commercial and industrial | Investment/Cash |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Commercial | Commercial and industrial | Other |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Commercial | Commercial construction |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 470,860 | 375,445 | 370,060
Commercial | Commercial construction | Real Estate |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 5,203 |  |
Commercial | Commercial construction | Blanket Lien |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Commercial | Commercial construction | Investment/Cash |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Commercial | Commercial construction | Other |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Commercial | Business banking |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 1,015,951 | 0 | 846,790
Commercial | Business banking | Real Estate |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 4,427 |  |
Commercial | Business banking | Blanket Lien |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 1,621 |  |
Commercial | Business banking | Investment/Cash |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Commercial | Business banking | Other |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 689 |  |
Consumer |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 1,584,834 |  | 1,624,356
Consumer | Commercial construction |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 15,343 |  | 8,390
Consumer | Consumer real estate |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 1,190,480 | $ 1,545,323 | $ 1,295,207
Consumer | Consumer real estate | Real Estate |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 398 |  |
Consumer | Consumer real estate | Blanket Lien |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Consumer | Consumer real estate | Investment/Cash |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | 0 |  |
Consumer | Consumer real estate | Other |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |
Loans held for investment, outstanding balance | $ 0 |  |

X
- 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
Name: | us-gaap_FinancingReceivableRecordedInvestmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before allowance for credit loss, of financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 79 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922352-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121599337&loc=SL82919230-210447 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 55 -Paragraph 80 -URI http://asc.fasb.org/extlink&oid=121647567&loc=SL82922355-210448 + Details
Name: | us-gaap_NotesReceivableGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_RealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=stba_BlanketLienMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=stba_InvestmentAndCashCollateralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=stba_OtherCollateralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=stba_CommercialAndIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=stba_BusinessBankingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=stba_ConsumerRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |