XML 39 R29.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Derivative Instruments and Hedging Activities (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract] |
Value of Derivative Assets and Derivative Liabilities | The following table indicates the amounts representing the value of derivative assets and derivative liabilities as of the dates presented:
| Derivatives (included in Other Assets) |  | Derivatives (included in Other Liabilities)
(dollars in thousands) | September 30, 2016 | December 31, 2015 |  | September 30, 2016 | December 31, 2015
Derivatives not Designated as Hedging Instruments: |  |  |  |  |
Interest Rate Swap Contracts- Commercial Loans |  |  |  |  |
Fair value | $ | 15,255 |  | $ | 11,295 |  |  | $ | 15,202 |  | $ | 11,276 |
Notional amount | 264,655 |  | 245,595 |  |  | 264,655 |  | 245,595 |
Collateral posted | — |  | — |  |  | 14,542 |  | 12,753 |
Interest Rate Lock Commitments- Mortgage Loans |  |  |  |  |
Fair value | 739 |  | 261 |  |  | — |  | — |
Notional amount | 21,699 |  | 9,894 |  |  | — |  | — |
Forward Sale Contracts- Mortgage Loans |  |  |  |  |
Fair value | — |  | — |  |  | 98 |  | 5 |
Notional amount | $ | — |  | $ | — |  |  | $ | 16,892 |  | $ | 9,800 |
Schedule of Gross Amounts of Derivative Assets and Derivative Liabilities | The following table indicates the gross amounts of commercial loan swap derivative assets and derivative liabilities, the amounts offset and the carrying values in the Consolidated Balance Sheets as of the dates presented:
| Derivatives (included in Other Assets) |  | Derivatives (included in Other Liabilities)
(dollars in thousands) | September 30, 2016 | December 31, 2015 |  | September 30, 2016 | December 31, 2015
Derivatives not Designated as Hedging Instruments: |  |  |  |  |
Gross amounts recognized | $ | 15,255 |  | $ | 11,295 |  |  | $ | 15,202 |  | $ | 11,276 |
Gross amounts offset | — |  | — |  |  | — |  | — |
Net amounts presented in the Consolidated Balance Sheets | 15,255 |  | 11,295 |  |  | 15,202 |  | 11,276 |
Gross amounts not offset(1) | — |  | — |  |  | (14,542 | ) | (12,573 | )
Net Amount | $ | 15,255 |  | $ | 11,295 |  |  | $ | 660 |  | $ | (1,297 | )
(1) Amounts represent posted collateral.
Amount of Gain or Loss Recognized in Income on Derivatives | The following table indicates the gain or loss recognized in income on derivatives for the periods presented:
| Three Months Ended September 30, |  | Nine Months Ended September 30,
(dollars in thousands) | 2016 | 2015 |  | 2016 | 2015
Derivatives not Designated as Hedging Instruments |  |  |  |  |
Interest rate swap contracts—commercial loans | $ | (87 | ) | $ | 29 |  |  | $ | 34 |  | $ | 20 |
Interest rate lock commitments—mortgage loans | 97 |  | 208 |  |  | 478 |  | 339 |
Forward sale contracts—mortgage loans | 106 |  | (143 | ) |  | (93 | ) | (69 | )
Total Derivatives Gain | $ | 116 |  | $ | 94 |  |  | $ | 419 |  | $ | 290 |

X
- Definition Schedule Of Derivative Assets And Liabilities Table [Text Block] + References No definition available. + Details
Name: | stba_ScheduleOfDerivativeAssetsAndLiabilitiesTableTableTextBlock
Namespace Prefix: | stba_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Tabular disclosure of the location and amount of derivative instruments and nonderivative instruments designated as hedging instruments reported before netting adjustments, and the amount of gain (loss) on derivative instruments and nonderivative instruments designated and qualified as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5618551-113959 + Details
Name: | us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the location and fair value amounts of derivative instruments (and nonderivative instruments that are designated and qualify as hedging instruments) reported in the statement of financial position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624163-113959 + Details
Name: | us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration