XML 152 R140.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Regulatory Matters - Narrative (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 USD ($)
Regulatory Capital Requirements Under Banking Regulations [Abstract] |
Total trust preferred securities | $ 29.0
Junior subordinated debt, included in Tier 2 capital | $ 25.0

X
- Definition Regulatory Capital Requirements Under Banking Regulations + References No definition available. + Details
Name: | stba_RegulatoryCapitalRequirementsUnderBankingRegulationsAbstract
Namespace Prefix: | stba_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Subordinated Borrowings Allowable in Computation of Net Capital1 + References No definition available. + Details
Name: | stba_SubordinatedBorrowingsAllowableinComputationofNetCapital1
Namespace Prefix: | stba_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash inflow from issuance of preferred stocks by a business trust or other special purpose entity, mainly established by a bank holding entity, to third party investors. The trust's assets are deeply subordinated debentures of the bank holding entity. Most trust preferred securities are subject to a mandatory redemption upon the repayment of the debentures. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfTrustPreferredSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration