XML 90 R87.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Allowance for Loan Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Details) - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Financing Receivable, Past Due [Line Items] |  |  |
Current | $ 7,060,617 |  | $ 5,890,141
Past Due | 81,791 |  | 58,878
Non- performing | 54,057 |  | 46,073
Total Loans | 7,142,408 |  | 5,949,019
Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current | 3,376,156 |  | 2,903,997
Past Due | 40,362 |  | 17,835
Non- performing | 29,140 |  | 12,052
Total Loans | 3,416,518 |  | 2,921,832
Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current | 1,700,522 |  | 1,482,473
Past Due | 20,311 |  | 10,943
Non- performing | 13,982 |  | 8,960
Total Loans | 1,720,833 |  | 1,493,416
Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current | 372,589 |  | 243,004
Past Due | 2,856 |  | 14,193
Non- performing | 737 |  | 14,193
Total Loans | 375,445 |  | 257,197
Residential mortgage |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current | 986,148 |  | 717,447
Past Due | 12,437 |  | 9,232
Non- performing | 7,519 |  | 7,128
Total Loans | 998,585 |  | 726,679
Home equity |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current | 533,367 |  | 465,152
Past Due | 4,981 |  | 6,410
Non- performing | 2,639 |  | 3,698
Total Loans | 538,348 |  | 471,562
Installment and other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current | 78,189 |  | 67,281
Past Due | 844 |  | 265
Non- performing | 40 |  | 42
Total Loans | 79,033 |  | 67,546
Consumer construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current | 8,390 |  | 8,416
Past Due | 0 |  | 0
Non- performing | 0 |  | 0
Total Loans | 8,390 |  | 8,416
Loans held for sale |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Current | 5,256 |  | 2,371
Past Due | 0 |  | 0
Non- performing | 0 |  | 0
Total Loans | 5,256 |  | 2,371
30-59 Days Past Due |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 17,992 |  | 8,473
30-59 Days Past Due | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 9,595 |  | 3,638
30-59 Days Past Due | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 2,940 |  | 1,000
30-59 Days Past Due | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 956 |  | 0
30-59 Days Past Due | Residential mortgage |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 2,016 |  | 1,584
30-59 Days Past Due | Home equity |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 2,059 |  | 2,103
30-59 Days Past Due | Installment and other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 426 |  | 148
30-59 Days Past Due | Consumer construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 0 |  | 0
30-59 Days Past Due | Loans held for sale |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 0 |  | 0
60-89 Days Past Due |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 5,985 |  | 4,332
60-89 Days Past Due | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 716 |  | 2,145
60-89 Days Past Due | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 1,946 |  | 983
60-89 Days Past Due | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 1,163 |  | 0
60-89 Days Past Due | Residential mortgage |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 1,727 |  | 520
60-89 Days Past Due | Home equity |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 141 |  | 609
60-89 Days Past Due | Installment and other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 292 |  | 75
60-89 Days Past Due | Consumer construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 0 |  | 0
60-89 Days Past Due | Loans held for sale |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 0 |  | 0
90 Days Past Due |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 3,757 | [1] | 0
90 Days Past Due | Commercial real estate |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 911 | [1] | 0
90 Days Past Due | Commercial and industrial |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 1,443 | [1] | 0
90 Days Past Due | Commercial construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 0 | [1] | 0
90 Days Past Due | Residential mortgage |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 1,175 | [1] | 0
90 Days Past Due | Home equity |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 142 | [1] | 0
90 Days Past Due | Installment and other consumer |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 86 | [1] | 0
90 Days Past Due | Consumer construction |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | 0 | [1] | 0
90 Days Past Due | Loans held for sale |  |  |
Financing Receivable, Past Due [Line Items] |  |  |
Past Due | $ 0 | [1] | $ 0
[1] | Represents acquired loans that were recorded at fair value at the acquisition date and remain performing.

X
- Definition Amount of financing receivable not past due. + References Reference 1: 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=118955255&loc=SL82922355-210448 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of financing receivable on nonaccrual status. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 16 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of financing receivable past due. + References Reference 1: 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=118955255&loc=SL82922355-210448 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919253-210447 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentPastDue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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_FinancingReceivableRecordedInvestmentPastDueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement. + References Reference 1: 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=119407570&loc=SL82919230-210447 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522 + Details
Name: | us-gaap_NotesReceivableNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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=us-gaap_ResidentialMortgageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables30To59DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables60To89DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |