XML 53 R59.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Allowance for Loan Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Detail) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 1,034,066 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer | $ 976,224 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer
% of Total | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage
Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 1,029,841 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 971,798 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
% of Total | 99.60%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.50%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 4,225 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 4,426 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
% of Total | 0.40%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.50%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Residential Mortgage [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 521,506 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember | 489,586 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember
% of Total | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember
Residential Mortgage [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 519,280 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 487,250 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
% of Total | 99.60%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.50%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Residential Mortgage [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 2,226 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 2,336 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
% of Total | 0.40%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.50%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_ResidentialMortgageMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Home Equity [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 442,396 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | 418,563 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
% of Total | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember
Home Equity [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 440,410 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 416,504 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
% of Total | 99.60%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.50%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Home Equity [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 1,986 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 2,059 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
% of Total | 0.40%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.50%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = us-gaap_HomeEquityMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Installment and Other Consumer [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 65,754 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember | 65,567 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember
% of Total | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember
Installment and Other Consumer [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 65,741 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 65,536 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
% of Total | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 99.90%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Installment and Other Consumer [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 13 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 31 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
% of Total | 0.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.10%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_InstallmentAndOtherConsumerMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
Consumer Construction [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 4,410 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember | 2,508 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember
% of Total | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember
Consumer Construction [Member] | Performing Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | 4,410 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 2,508 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
% of Total | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember | 100.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PerformingFinancingReceivableMember
Consumer Construction [Member] | Nonperforming Financing Receivable [Member] |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | $ 0 us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember
% of Total | 0.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember | 0.00%stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = stba_ConsumerConstructionMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_NonperformingFinancingReceivableMember

X
- Definition Loans and leases receivable gross carrying amount consumer percentage. + References No definition available. + Details
Name: | stba_LoansAndLeasesReceivableGrossCarryingAmountConsumerPercentage
Namespace Prefix: | stba_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Reflects the aggregate gross carrying amount of all consumer loans and leases held in portfolio, prior to deducting deferred income and the allowance for losses on consumer loans and leases. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5066-111524 + Details
Name: | us-gaap_LoansAndLeasesReceivableGrossCarryingAmountConsumer
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_PerformingFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |