XML 74 R34.htm IDEA: XBRL DOCUMENT
v3.20.1

Commitments and Contingencies (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract] |
Schedule of Commitments and Letters of Credit | The following table sets forth our commitments and letters of credit as of the dates presented:
(dollars in thousands) | March 31, 2020 |  |  | December 31, 2019 |
Commitments to extend credit |  | $ | 1,967,190 |  |  |  | $ | 1,910,805 |
Standby letters of credit |  | 85,021 |  |  |  | 80,040 |
Total |  | $ | 2,052,211 |  |  |  | $ | 1,990,845 |
Unfunded Loan Commitments, Allowance For Credit Loss | The activity in the allowance for credit losses on unfunded loan commitments for the three months ended March 31, 2020 was as follows:
(dollars in thousands) |  | Total
Three months ended March 31, 2020 |  |
Allowance for credit losses on unfunded loan commitments: |  |
Balance at beginning of period |  | $ | 3,112 |
Impact of adopting ASU 2016-13 |  | 1,349 |
January 1, 2020 |  | 4,461 |
Provision for credit losses |  | 1,616 |
March 31, 2020 |  | $ | 6,077 |

X
- Definition Commitments and Letters of Credit [Table Text Block] + References No definition available. + Details
Name: | stba_CommitmentsandLettersofCreditTableTextBlock
Namespace Prefix: | stba_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Off Balance Sheet Liability, Allowance For Credit Loss + References No definition available. + Details
Name: | stba_OffBalanceSheetLiabilityAllowanceForCreditLossTableTextBlock
Namespace Prefix: | stba_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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