LONG-TERM OBLIGATIONS - Other Long-term Obligations (Details) - USD ($) $ in Thousands |
12 Months Ended | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Oct. 10, 2007 |
[5] | ||||||||||||||
Debt Instruments [Abstract] | |||||||||||||||||
Subordinated notes, net of unamortized debt issuance costs | [1] | $ 98,248 | $ 98,100 | ||||||||||||||
Trust preferred subordinated debentures | [2] | 60,241 | 60,236 | ||||||||||||||
Total long-term obligations | 158,489 | 158,336 | |||||||||||||||
5.50% Subordinated Notes | |||||||||||||||||
Debt Instruments [Abstract] | |||||||||||||||||
Subordinated notes, net of unamortized debt issuance costs | [1],[3] | 98,248 | 98,100 | ||||||||||||||
Unamortized debt issuance expense | 1,800 | 1,900 | |||||||||||||||
Southside Statutory Trust III, net of unamortized debt issuance costs | |||||||||||||||||
Debt Instruments [Abstract] | |||||||||||||||||
Trust preferred subordinated debentures | [2],[4] | 20,549 | 20,544 | ||||||||||||||
Unamortized debt issuance expense | 70 | 75 | |||||||||||||||
Southside Statutory Trust IV | |||||||||||||||||
Debt Instruments [Abstract] | |||||||||||||||||
Trust preferred subordinated debentures | 23,196 | 23,196 | [2] | ||||||||||||||
Southside Statutory Trust V | |||||||||||||||||
Debt Instruments [Abstract] | |||||||||||||||||
Trust preferred subordinated debentures | 12,887 | 12,887 | [2] | ||||||||||||||
Magnolia Trust Company I | |||||||||||||||||
Debt Instruments [Abstract] | |||||||||||||||||
Trust preferred subordinated debentures | $ 3,609 | [5] | $ 3,609 | [2] | $ 3,600 | ||||||||||||
Minimum | 5.50% Subordinated Notes | |||||||||||||||||
Debt Instruments [Abstract] | |||||||||||||||||
Long-term debt, remaining maturity | 1 year | ||||||||||||||||
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