Loans and Loans Held for Sale - Summary of Nonperforming Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Nonperforming Assets
Nonaccrual loans	$ 7,021	$ 12,387
Nonaccrual TDRs	5,436	10,067
Total nonaccrual loans	12,457	22,454
OREO	166us-gaap_OtherRealEstate	410us-gaap_OtherRealEstate
Total Nonperforming Assets	$ 12,623stba_NetNonperformingAssets	$ 22,864stba_NetNonperformingAssets

Financing receivable recorded investment nonaccrual trouble debt restructured.

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- Definition

Financing receivable recorded investment non performing.

+ References

No definition available.

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- Definition

Net nonperforming assets.

+ References

No definition available.

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- 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 (d)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524

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- Definition

Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

+ 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 210.9-03.10(4))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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