XML 92 R76.htm IDEA: XBRL DOCUMENT v3.8.0.1

Allowance for Loan Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 5,730,074	$ 5,563,123
Past Due	35,860	52,089
Non- performing	23,938	42,635
Total Loans	5,765,934	5,615,212
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	2,681,395	2,479,513
Past Due	4,599	18,963
Total Loans	2,685,994	2,498,476
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,426,754	1,391,475
Past Due	6,512	9,560
Total Loans	1,433,266	1,401,035
Commercial construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	377,968	450,410
Past Due	6,366	5,474
Total Loans	384,334	455,884
Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	687,195	689,635
Past Due	11,579	12,347
Total Loans	698,774	701,982
Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	480,956	476,866
Past Due	6,370	5,418
Total Loans	487,326	482,284
Installment and other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	66,770	65,525
Past Due	434	327
Total Loans	67,204	65,852
Consumer construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	4,551	5,906
Past Due	0	0
Total Loans	4,551	5,906
Loans held for sale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	4,485	3,793
Past Due	0	0
Total Loans	4,485	3,793
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	9,123	6,598
30-59 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	997	2,032
30-59 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	420	1,061
30-59 Days Past Due | Commercial construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,473	547
30-59 Days Past Due | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,975	1,312
30-59 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,065	1,470
30-59 Days Past Due | Installment and other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	193	176
30-59 Days Past Due | Consumer construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
30-59 Days Past Due | Loans held for sale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	2,799	2,856
60-89 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	134	759
60-89 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	446	428
60-89 Days Past Due | Commercial construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	20	0
60-89 Days Past Due | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	1,439	1,117
60-89 Days Past Due | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	590	509
60-89 Days Past Due | Installment and other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	170	43
60-89 Days Past Due | Consumer construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
60-89 Days Past Due | Loans held for sale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	23,938	42,635
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	3,468	16,172
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	5,646	8,071
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	3,873	4,927
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	7,165	9,918
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	3,715	3,439
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Installment and other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	71	108
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans held for sale
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- performing	$ 0	$ 0

X

- Definition

Financing receivables that are current.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953401-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Recorded Investment in financing receivables that are past due at the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953401-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentPastDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentPastDueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_LoansReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=stba_CommercialAndIndustrialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_ConstructionLoansMember
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_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityLoanMember
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=stba_ConsumerConstructionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=stba_LoansHeldforSaleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables30To59DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables60To89DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: