Note 9 - Deposits (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Expense, Time Deposits, 250,000 or More	$ 161	$ 231	$ 313
Related Party Deposit Liabilities	28,500	30,500
Deposit Liabilities Reclassified as Loans Receivable	$ 614	$ 449

Interest expense incurred on time deposits, including certificates of deposits, of $250,000 or more in domestic offices.

No definition available.

+ Details

Name:	sybt_InterestExpenseTimeDeposits250000OrMore
Namespace Prefix:	sybt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of deposits held by the entity that have been reclassified as loan balances receivable, for example, but not limited to, overdrafts receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=50488274&loc=d3e64164-112818

+ Details

Name:	us-gaap_DepositLiabilitiesReclassifiedAsLoansReceivable1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of deposits held by the entity for a related party (entity, shareholder, employee).

+ References

Reference 1: 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.(k))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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