CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Interest income
Loans	$ 66,736	$ 69,973	$ 70,679
Investment securities - taxable	64	91	1,055
Investment securities - tax exempt	12,520	10,889	7,607
Mortgage-backed and related securities	51,467	50,130	65,463
FHLB stock and other investments	233	259	235
Other interest earning assets	18	32	154
Total interest income	131,038	131,374	145,193
Interest expense
Deposits	15,647	18,969	22,682
Short-term obligations	6,577	7,563	4,696
Long-term obligations	13,407	18,775	25,294
Total interest expense	35,631	45,307	52,672
Net interest income	95,407	86,067	92,521
Provision for loan losses	7,496	13,737	15,093
Net interest income after provision for loan losses	87,911	72,330	77,428
Noninterest income
Deposit services	15,943	16,819	17,629
Gain on sale of securities available for sale	11,795	25,789	33,446
Gain on sale of securities carried at fair value through income	937	0	0
Total other-than-temporary impairment losses	0	(39)	(5,730)
Portion of loss recognized in other comprehensive income (before taxes)	0	(36)	2,730
Net impairment losses recognized in earnings	0	(75)	(3,000)
Fair value gain (loss) - securities	6,693	(598)	0
FHLB advance option impairment charges	(8,923)	0	0
Gain on sale of loans	1,230	1,751	1,240
Trust income	2,610	2,368	2,456
Bank owned life insurance income	1,087	1,155	1,724
Other	3,950	3,589	3,179
Total noninterest income	35,322	50,798	56,674
Noninterest expense
Salaries and employee benefits	45,421	43,957	42,505
Occupancy expense	7,205	6,780	6,372
Equipment expense	2,055	1,899	1,718
Advertising, travel and entertainment	2,414	2,319	2,344
ATM and debit card expense	987	825	1,296
Director fees	914	950	785
Supplies	746	902	863
Professional fees	2,160	2,015	2,218
Postage	725	800	872
Telephone and communications	1,325	1,443	1,424
FDIC Insurance	1,817	2,909	3,943
Other	6,579	6,515	7,290
Total noninterest expense	72,348	71,314	71,630
Income before income tax expense	50,885	51,814	62,472
Provision (benefit) for income tax expense
Current	11,665	11,100	16,816
Deferred	(1,271)	656	(207)
Total income taxes	10,394	11,756	16,609
Net income	40,491	40,058	45,863
Less: Net income attributable to the noncontrolling interest	(1,358)	(955)	(1,467)
Net income attributable to Southside Bancshares, Inc	$ 39,133	$ 39,103	$ 44,396
Earnings per common share - basic (in dollars per share)	$ 2.38	$ 2.37	$ 2.71
Earnings per common share - diluted (in dollars per share)	$ 2.38	$ 2.37	$ 2.68
Dividends declared per common share (in dollars per share)	$ 0.90	$ 0.85	$ 0.75