XML 43 R31.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Commitments and Contingencies (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract] |
Commitments and Letters of Credit | The following table sets forth the commitments and letters of credit as of the dates presented:
(dollars in thousands) | March 31, 2015 |  |  | December 31, 2014 |
Commitments to extend credit | $ | 1,370,341 |  |  | $ | 1,158,628 |
Standby letters of credit | 97,386 |  |  | 73,584 |
Total | $ | 1,467,727 |  |  | $ | 1,232,212 |

X
- Definition Summary Of Contract Or Notional Amounts Of Commitments To Extend Credit And Letters Of Credit Table [Text Block] + References No definition available. + Details
Name: | stba_SummaryOfContractOrNotionalAmountsOfCommitmentsToExtendCreditAndLettersOfCreditTableTableTextBlock
Namespace Prefix: | stba_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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