XML 81 R54.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Commitments and Contingencies (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract] |
Commitments and Letters of Credit | The following table sets forth our commitments and letters of credit as of the dates presented:
| December 31,
(dollars in thousands) | 2019 |  |  | 2018 |
Commitments to extend credit | $ | 1,910,805 |  |  | $ | 1,464,892 |
Standby letters of credit | 80,040 |  |  | 77,134 |
Total | $ | 1,990,845 |  |  | $ | 1,542,026 |

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