XML 63 R47.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Long-Term Borrowings and Subordinated Debt (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2017
Debt Disclosure [Abstract] |
Schedule of Long-Term Borrowings, Interest Expense and Weighted Average Interest Rate | The following table represents the balance of long-term borrowings, the weighted average interest rate as of December 31 and interest expense for the years ended December 31:
(dollars in thousand) | 2017 |  | 2016 |  | 2015
Long-term borrowings | $ | 47,301 |  |  | $ | 14,713 |  |  | $ | 117,043 |
Weighted average interest rate | 1.88 | % |  | 2.91 | % |  | 0.81 | %
Interest expense | $ | 463 |  |  | $ | 670 |  |  | $ | 790 |
Schedule of Annual Maturities and Average Interest Rate of Long-Term Debt | Scheduled annual maturities and average interest rates for all of our long-term debt for each of the five years subsequent to December 31, 2017 and thereafter are as follows:
(dollars in thousands) | Balance |  |  | Average Rate |
2018 | $ | 2,496 |  |  | 3.60 | %
2019 | 37,514 |  |  | 1.60 | %
2020 | 2,004 |  |  | 3.22 | %
2021 | 1,057 |  |  | 3.44 | %
2022 | 529 |  |  | 4.50 | %
Thereafter | 3,701 |  |  | 1.96 | %
Total | $ | 47,301 |  |  | 1.88 | %
Schedule of Junior Subordinated Debt Securities and Interest Expense | The following table represents the composition of junior subordinated debt securities at December 31 and the interest expense for the years ended December 31:
| 2017 |  | 2016 |  | 2015
(dollars in thousands) | Balance |  |  | Interest Expense |  |  | Balance |  |  | Interest Expense |  |  | Balance |  |  | Interest Expense |
2006 Junior subordinated debt | $ | 25,000 |  |  | $ | 708 |  |  | $ | 25,000 |  |  | $ | 580 |  |  | $ | 25,000 |  |  | $ | 554 |
2008 Junior subordinated debt—trust preferred securities | 20,619 |  |  | 955 |  |  | 20,619 |  |  | 854 |  |  | 20,619 |  |  | 773 |
Total | $ | 45,619 |  |  | $ | 1,663 |  |  | $ | 45,619 |  |  | $ | 1,434 |  |  | $ | 45,619 |  |  | $ | 1,327 |
Schedule of Junior Subordinated Debt Securities | The following table summarizes the key terms of our junior subordinated debt securities:
(dollars in thousands) | 2006 Junior Subordinated Debt |  | 2008 Trust Preferred Securities
Junior Subordinated Debt | $25,000 |  | —
Trust Preferred Securities | — |  | $20,619
Stated Maturity Date | 12/15/2036 |  | 3/15/2038
Optional redemption date at par | Any time after 9/15/2011 |  | Any time after 3/15/2013
Regulatory Capital | Tier 2 |  | Tier 1
Interest Rate | 3 month LIBOR plus 160 bps |  | 3 month LIBOR plus 350 bps
Interest Rate at December 31, 2017 | 2.92% |  | 4.82%

X
- Definition Schedule of junior subordinated debt by trust. + References No definition available. + Details
Name: | stba_ScheduleOfJuniorSubordinatedDebtByTrustTableTableTextBlock
Namespace Prefix: | stba_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule of long term debt interest expense. + References No definition available. + Details
Name: | stba_ScheduleOfLongTermDebtInterestExpenseTableTableTextBlock
Namespace Prefix: | stba_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_DebtDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(e),(f)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644 + Details
Name: | us-gaap_ScheduleOfDebtInstrumentsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the combined aggregate amount of maturities and sinking fund requirements for all long-term borrowings for each of the five years following the date of the latest balance sheet date presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 + Details
Name: | us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration