XML 75 R60.htm IDEA: XBRL DOCUMENT
v3.20.2

Allowance for Credit Losses - Collateral Dependent Loans by Class of Loan (Details) - USD ($) $ in Thousands | Jun. 30, 2020 | Jan. 01, 2020 | Dec. 31, 2019
--- | --- | --- | ---
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | $ 7,548,558 | [1] |  | $ 7,137,152
Real Estate |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 66,728 |  |  |
Blanket Lien |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 4,630 |  |  |
Investment/Cash |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Other |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 689 |  |  |
Commercial | Commercial real estate |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 2,862,103 | [1] | $ 3,416,518 | 3,059,592
Commercial | Commercial real estate | Real Estate |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 55,447 |  |  |
Commercial | Commercial real estate | Blanket Lien |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 40 |  |  |
Commercial | Commercial real estate | Investment/Cash |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Commercial real estate | Other |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Commercial and industrial |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 1,682,676 | [1] | 1,720,833 | 1,480,529
Commercial | Commercial and industrial | Real Estate |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 2,762 |  |  |
Commercial | Commercial and industrial | Blanket Lien |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 3,694 |  |  |
Commercial | Commercial and industrial | Investment/Cash |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Commercial and industrial | Other |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Commercial construction |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 453,098 | [1] | 375,445 | 370,060
Commercial | Commercial construction | Real Estate |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 5,215 |  |  |
Commercial | Commercial construction | Blanket Lien |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Commercial construction | Investment/Cash |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Commercial construction | Other |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Business banking |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 1,268,835 | [1] | $ 0 | $ 846,790
Commercial | Business banking | Real Estate |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 2,906 |  |  |
Commercial | Business banking | Blanket Lien |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 896 |  |  |
Commercial | Business banking | Investment/Cash |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Business banking | Other |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 689 |  |  |
Commercial | Consumer real estate | Real Estate |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 398 |  |  |
Commercial | Consumer real estate | Blanket Lien |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Consumer real estate | Investment/Cash |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | 0 |  |  |
Commercial | Consumer real estate | Other |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |
Portfolio loans, net of unearned income | $ 0 |  |  |
[1] | We had 2,360 loans that were modified totaling $1.4 billion under the CARES Act at June 30, 2020. These customers were not considered past due as a result of their delayed payments. Upon exiting the loan modification deferral program, the measurement of loan delinquency will resume where it left off upon entry into the program. Due to the modification program, this delinquency table may not accurately reflect the credit risk associated with these loans.

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_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=stba_ConsumerRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |