XML 64 R54.htm IDEA: XBRL DOCUMENT v3.19.2

Allowance for Loan Losses - Recorded Investment in Commercial Loan Classes by Internally Assigned Risk Ratings (Details) - Commercial - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 4,733,825	$ 4,672,445
Total percentage of recorded investment in commercial loan	100.00%	100.00%
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 4,490,208	$ 4,403,909
Total percentage of recorded investment in commercial loan	94.90%	94.30%
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 105,708	$ 87,344
Total percentage of recorded investment in commercial loan	2.20%	1.80%
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 137,909	$ 181,192
Total percentage of recorded investment in commercial loan	2.90%	3.90%
Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 2,906,895	$ 2,921,832
Total percentage of recorded investment in commercial loan	100.00%	100.00%
Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 2,750,338	$ 2,776,292
Total percentage of recorded investment in commercial loan	94.60%	95.00%
Commercial real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 63,993	$ 54,627
Total percentage of recorded investment in commercial loan	2.20%	1.90%
Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 92,564	$ 90,913
Total percentage of recorded investment in commercial loan	3.20%	3.10%
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 1,559,727	$ 1,493,416
Total percentage of recorded investment in commercial loan	100.00%	100.00%
Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 1,483,519	$ 1,394,427
Total percentage of recorded investment in commercial loan	95.10%	93.40%
Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 34,527	$ 25,368
Total percentage of recorded investment in commercial loan	2.20%	1.70%
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 41,681	$ 73,621
Total percentage of recorded investment in commercial loan	2.70%	4.90%
Commercial construction
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 267,203	$ 257,197
Total percentage of recorded investment in commercial loan	100.00%	100.00%
Commercial construction | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 256,351	$ 233,190
Total percentage of recorded investment in commercial loan	95.90%	90.70%
Commercial construction | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 7,189	$ 7,349
Total percentage of recorded investment in commercial loan	2.70%	2.80%
Commercial construction | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases receivables, recorded investment	$ 3,664	$ 16,658
Total percentage of recorded investment in commercial loan	1.40%	6.50%

X

- Definition

Loans and leases receivable gross carrying amount commercial percentage.

+ References

No definition available.

+ Details

Name:	stba_LoansAndLeasesReceivableGrossCarryingAmountCommercialPercentage
Namespace Prefix:	stba_
Data Type:	num:percentItemType
Balance Type:	na
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_FinancingReceivableRecordedInvestmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

+ Details

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

X

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_PassMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SpecialMentionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_SubstandardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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: