- Off-Balance-Sheet Arrangements, Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	$ 432,099	$ 379,477
Securities:
Unsettled trades to purchase securities	13,096	5,982	1,032
Unsettled trades to sell securities	1,792sbsi_UnsettledTradesToSellSecurities	57,202sbsi_UnsettledTradesToSellSecurities	0sbsi_UnsettledTradesToSellSecurities
Deposits:
Unsettled issuances of brokered CDs	0sbsi_UnsettledIssuancesofBrokeredCDs	0sbsi_UnsettledIssuancesofBrokeredCDs
Standby Letters of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	6,387	6,222
Commitments to Extend Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off-balance-sheet risk, at fair value	$ 425,712	$ 373,255

Amount of brokered CDs sold that were not settled by the end of the period. The amount recorded is the selling price including any accrued interest.

No definition available.

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Period Type:	instant

- Definition

Amount of securities purchased that were not settled by the end of the period. The amount recorded is the purchase price including any accrued interest. This asset is collected upon delivery of the securities.

+ References

No definition available.

+ Details

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- Definition

Amount of securities sold that were not settled by the end of the period. The amount recorded is the selling price including any accrued interest. This asset is collected upon delivery of the securities.

+ References

No definition available.

+ Details

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- 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=35750535&loc=d3e13433-108611

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