Note 15 - Commitments and Contingent Liabilities (Details Textual) $ in Thousands	9 Months Ended
Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Loss Contingency Accrual	$ 350
ATM [Member]
Long-term Purchase Commitment, Minimum Quantity Required	29
Long-term Purchase Commitment, Amount	$ 1,200
Standby Letters of Credit [Member]
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	$ 17,600	$ 15,600
Standby Letters of Credit [Member] \| Minimum [Member]
Guarantee Obligations, Agreement Term	1 year
Standby Letters of Credit [Member] \| Maximum [Member]
Guarantee Obligations, Agreement Term	2 years
Unasserted Claim [Member]
Loss Contingency Accrual	$ 266
Commitments to Extend Credit and Standby Letters of Credit [Member]
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	$ 709,700	$ 628,300

Represents the term of agreements entered into by the entity for undertaking guarantee obligation.

No definition available.

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Namespace Prefix:	sybt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The fair value of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The minimum amount the entity agreed to spend under the long-term purchase commitment.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of units of goods that must be purchased within the specified time period of the agreement to avoid penalties or unfavorable effects on pricing, among other adverse consequences.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
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